Mo3-28

Mo3-29
POLAR MOLECULES IN HELIUM CLUSTERS: BOSONIC VERSUS FERMIONIC ENVIRONMENTS M. P. de Lara-Castells, R. Prosmiti, G. Delgado-Barrio, D. Lpez-Durn, and P. Villarreal

Mo3-30

SWEEPING-OUT-ELECTRONS EFFECT LARGE MOLECULES AND CLUSTERS Edward S. Parilis

IMPACT

Mo3-31
FRAGMENTATION AND FORMATION AS PHASE TRANSITION IN FULLERENES Adilah Hussien, Ilia Solov'yov, Andrey V. Solov'yov and Walter Greiner

Mo3-32

DFT CALCULATIONS OF GOLD CLUSTERS WITH S, Se and Te COMPOUNDS Pablo Lpez-Tarifa, Fernando Martn and Manuel Alcam QUANTUM MONTE CARLO SIMULATION OF SMALL BOSONHELIUM CLUSTERS WITH FERMION-HELIUM IMPURITIES Dr. Cono Di Paola, Prof. Gabriele Morosi, Dr. Dario Bressanini QUANTUM STRUCTURING AND MICROENERGETICS OF IONIC 4 DOPANTS IN HE DROPLETS FROM STOCHASTIC CALCULATIONS E. Coccia, E. Bodo, F.A. Gianturco SPATIAL ARRANGEMENTS AND STABILITY SHELLS FOR BOSONIC He CLUSTERS AROUND IONIC IMPURITIES: A GENETIC ALGORITHM STUDY. F. Marinetti, E. Bodo, F.A. Gianturco, E. Yurtserver, M. Yurtserver, E. Yildrim STRUCTURE OF THE PCBM FULLERENE DERIVATIVE AND ITS DIMERS Yang Wang, Manuel Alcam, Fernando Martn PHOTO ATOMIC INDUCED PROCESSES IN DRYFILM COATINGS AND NANOPOROUS SILICA A. Burchianti, A. Bogi, A. Cappello, C. de Mauro, S. Di Renzone, A. Khanbekyan, C. Marinelli, C. Maibohm, E. Mariotti, L. Moi

Mo3-33

Mo3-34

Mo3-35

Mo3-36

Mo3-37

Mo3-38
EXCITATION AND IONIZATION OF CLUSTERS OF CHIRAL FLUORINATED MOLECULES BY R2PI SPECTROSCOPY A. Giardini, F. Rondino, A. Paladini, M. Speranza, S. Piccirillo, M. Satta

Mo3-39

PHOTOABSORPTION CROSS SECTIONS FOR THE FULLERENE IONS C60+ AND C60++. A.K. Belyaev, V.K. Ivanov, R.G. Polozkov, A.S. Tiukanov, A.V. Solov'yov and W. Greiner STABILITY OF MULTIPLY CHARGED FULLERENE DIMERS H. Zettergren, S. Daz-Tendero, M. Alcam and F. Martn AB INITIO INTERMOLECULAR POTENTIALS AND DYNAMICS OF Rg2-DIHALOGEN CLUSTERS R. Prosmiti, A. Valds, C. DiezPardos, P. Villarreal, G. DelgadoBarrio ATOM-SURFACE VAN DER WAALS INTERACTION IN THE NANOMETRIC RANGE A. Laliotis, I. Maurin, P. Todorov, I. Hamdi, G. Dutier, S. Saltiel, M.-P. Gorza, M. Fichet, D. Bloch and M. Ducloy THE LATTICE PHONON STUDIES OF CCVD GROWN CnTs R. Malekfar and H. Asadi ENERGETICS AND STABILITY OF CARBON NANOTUBES OF DIFFERENT CHIRALITIES Maneesh Mathew, Ilia A. Solovyov, Andrey V. Solovyov and Walter Greiner

5a-4 (We1-7)

Laser induced molecular alignment of ethylene
A. Rouze, S. Gurin, B. Lavorel, and O. Faucher Institut Carnot de Bourgogne, UMR 5209 CNRS - Universit de Bourgogne, BP 47870, 21078 Dijon cedex, France
Molecular orientation and alignment play a key role in strong field-molecule interactions, chemical reactions, and gas-phase solid interactions. For example, in chemistry, the product of a reaction can be maximized by aligning molecules, or in gas-phase solid interaction, stereodynamic effects on surface adsorption processes can be studied by guiding molecules [1]. To investigate the effects of molecular alignment on these processes, it is necessary to control the rotational degrees of freedom of the molecules. The last years, it has been established that strong non-resonant laser pulses of duration >> /B, with B the rotational constant of the molecule, align molecules during the interaction with the field, while impulsive pulses ( << /B) yield to postpulse transient alignment revivals [2]. These effects have been studied both theoretically and experimentally, principally in linear molecules. However, lot of applications implies asymmetric top molecules. It is necessary therefore to implement experiments in order to control their rotational motions. Here, we show that a single elliptically polarized laser pulse with appropriate ellipticity allows to align the three axes of an asymmetric top molecule. We present a theoretical model where we define the ellipticity that maximizes simultaneously the alignment of two molecular axes, and therefore the 3-D alignment. Experimentally, field free 3-D molecular alignment has been probed using the optical kerr effect in a molecular jet of ethylene. One-dimensional alignment experiments have been first conducted with linearly polarized laser pulses in order to estimate peak intensity and temperature. Then, using elliptically polarized laser pulses, we have induced and measured three-dimensional alignment of ethylene.
References [1] L. Vattuone, A. Gerbi, M. Rocca, U. Valbusa, F. Pirani, D. Cappelletti, F. Vecchiocattivi, Angew. Chem. Int. Ed. 43, 5200 (2004). [2] H. Stapelfeldt and T. Seideman, Rev. Mod. Phys. 75, 543 (2003).

5b-4 (We3-29)

COLLECTIVE EXCITATIONS AND INSTABILITY OF AN OPTICAL LATTICE DUE TO UNBALANCED PUMPING
P. Domokos1 , J. K. Asb th1,2 , H. Ritsch2 o Research Institute of Solid State Physics and Optics, Hungarian Academy of Sciences, H-1525 Budapest P.O. Box 49, Hungary 2 Institut f r Theoretische Physik, Universit t Innsbruck, Technikerstr. 25, A-6020 u a Innsbruck, Austria Optical lattices (OL) are perfectly periodic arrays of particles trapped by the standing wave interference pattern of several laser beams. They have important applications as model systems for solid state physics as well as for quantum information science. The back-action of the trapped particles on the trap light is carefully avoided in most OL experiments. However, it is known to give rise to intriguing phenomena in related systems, e.g., cavity cooling, mirror cooling, and optical binding. For OLs this back-action has been predicted [1] and observed [2, 3] to reduce the lattice constant d compared to the naive expectation. We will consider the effects of optical back-action in one-dimensional OLs, brought about by tuning a hitherto neglected parameter: the relative intensity of the lattice beams. Introducing an asymmetry in the trap not only enhances the reduction of the lattice constant, but, more importantly, alters the interaction between the trapped particles mediated by the light. The asymmetry gives rise to traveling density waves even in the presence of arbitrarily strong viscous damping [6]. This is directly related to the wavelike excitations in other crystals driven far from equilibrium, such as arrays of vortices in a type-II superconductor [4], and trains of water drops dragged by oil [5]. These waves arise resonantly at specic values of the asymmetry, and destabilize the lattice at a critical asymmetry that decreases sharply as the lattice size is increased.

6b-5 (Mo5-5)

Single Photon-Induced Symmetry Breaking of H2 Dissociation
F. Martn1, J. Fernndez1, T. Havermeier2, L. Foucar2, Th. Weber2, K. Kreidi2, M. Schffler2, L. Schmidt2, T. Jahnke2, O. Jagutzki2, A. Czasch2, E. P. Benis3, T. Osipov4, A. L. Landers5, A. Belkacem4, M. H. Prior4, H. Schmidt-Bcking2, C. L. Cocke3, R. Drner2
Departamento de Qumica, C-9, Universidad Autnoma de Madrid, 28049 Madrid, Spain. Institut fr Kernphysik, University Frankfurt, Max von Laue Strasse 1, D-60438 Frankfurt, Germany. 3 Department of Physics, Kansas State University, Cardwell Hall, Manhattan, KS 66506, USA. 4 Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. 5 Department of Physics, Auburn University, Auburn, AL 36849, USA.
The indistinguishableness of the two protons in the dissociating H2+ molecule prohibits the electron to prefer one nucleus for the generation of the neutral hydrogen. In this contribution a method is shown to break this symmetry via the population of doubly excited states. In March 2005 an experiment was performed at the Advanced Light Source in Berkeley to observe the dissociating channels in hydrogen and deuterium molecules. The COLTRIMS method allows a kinematically complete measurement so that a map of all appearing states could be obtained. References [1] Martn et all., Science, 315, 629 (2007)

7b-4 (Th3-11)

Many-Body Dynamics of Repulsively Bound Pairs of Particles in a Periodic Potential
David Petrosyan,1,2 Bernd Schmidt,1 James R. Anglin,1 and Michael Fleischhauer1
Fachbereich Physik, Technische Universitt Kaiserslautern, D-67663 Kaiserslautern, Germany 2 Institute of Electronic Structure & Laser, FORTH, 71110 Heraklion, Crete, Greece
Recently, Winkler et al. [Nature 441, 853 (2006)] have observed repulsively bound atom pairs in an optical lattice. In a tight-binding periodic potential described by the Bose-Hubbard model, when the on-site repulsion between the particles exceeds their inter-site tunneling rate, such dimers are well localized at single sites and are stable over the time scale on which the energy dissipation is negligible. We derive an effective many-body Hamiltonian for a lattice loaded with dimers only, and discuss its implications for dynamics of the system. We show that strong on-site repulsion and nearest-neighbor attraction favor clusters of dimers with minimum surface area and uniform, commensurate filling, representing thus incompressible droplets of a lattice liquid.

8b-2 (Mo3-15)

Resonances in Transition Metal Complexes by TDDFT calculations
P. Decleva, G. Fronzoni and M. Stener Universita di Trieste Dipartimento di Scienze Chimiche,Via Giorgieri, 1 I-34127 Trieste, Italy
Time Dependent Density Functional Theory (TDDFT) has been shown to be a powerful and accurate description of photoionization processes, including interchannel coupling, in small systems [1,2]. A new direct algorithm for the solution of the equations in complex molecules has been presented [3], which eliminates convergence problems which hinder application of the classical SCF approach to large systems, and a parallel implementation is being developed. Applications to the description of resonances, both shape and autoionization, in organometallic systems [4] will be presented, together with a discussion of chemical effects on the position and strength of the resonances.
References [1] A. Zangwill and P. Soven, Phys. Rev. A, 21, 1561 (1980) [2] M. Stener and P. Decleva, J. Chem. Phys, 112, 10871 (2000) [3] M. Stener, G. Fronzoni and P. Decleva, J. Chem. Phys, 122, 234301 (2005) [4] J. C. Green and P. Decleva, Coord. Chem. Rev., 249, 209 (2005)

8b-3 (Mo3-2)

NON-METALLIC BEHAVIOR OF C60 ELECTRON SHELL
M. Ya. Amusia1, 2 and A. S. Baltenkov 3
Racah Institute of Physics, the Hebrew University, Jerusalem 91904, Israel 2 Ioffe Physical-Technical Institute, St.-Petersburg 194021, Russia 3 Arifov Institute of Electronics, Tashkent, 700125, Uzbekistan
The dynamical and static dipole polarizabilities of the C60 molecule have been calculated on the basis of the experimental data on the cross section of the fullerene photoabsorption [1]. It has been shown that the fullerene shell in the static electric field behaves most likely as a set of separate carbon atoms, rather than as a conducting sphere [2]. We demonstrate that by studying photoabsorption cross-section of a mesoscopic object one can conclude whether its electron system forms a conductor or dielectric. Of course, these notions characterize the ability of the object to conduct electricity and are applicable, only to macroscopic bodies. However, for mesoscopic objects that include many atoms, the feature of conductivity can also become meaningful starting from the certain number of constituent atoms. This makes sensible the question whether a mesoscopic system behaves as a conductor, i.e. whether its electrons can move freely under the action of an external electric field. As a feature that characterizes a conductor we use a quite natural definition that a static external electric field cannot penetrate inside a conducting body. As an object of investigation and as a particular example of the mesoscopic system, in this talk we choose the fullerene C60 molecule. We calculate the effective electric field E eff ( ) that is at the fullerene center when the external electric field E( ) with frequency is applied to C60. The modification of the external field comes from the effect of the dynamic dipole polarizability d ( ) of the fullerene C60 that is expressed via its total photoionization cross-section ( ). We calculate the frequency dependence of the ratio ( ) E eff ( ) / E( ) and then investigate whether (0) is equal to zero or not.

References [1] F. B. Rosmej, R. Stamm, and V. S. Lisitsa, Europhys. Lett., 73, 342 (2006) [2] N. Vaeck, M. Desouter-Lecomte, and J. Livin, J. Phys. B, 32, 409 (1999)
Complex electron dynamic in He+-He-collisions at 60 keV/u
M. S. Schffler1*, J. Titze1, L. Ph. H. Schmidt1, O. Jagutzki1, T. Jahnke1, S. Otranto2, R. Olson2, R. Drner1 and H. Schmidt-Bcking1
Institut fr Kernphysik, Universitt Frankfurt, 60486 Frankfurt, Germany 2 University of Missouri, Rolla, USA
At high projectile velocities (vP > 3 a. u.) the dynamic of transfer ionization (TI) processes is nearly independent of the projectile. This approximation is also valid for lower velocities, except some post collision effects (PCI). The final state of a transfer ionization leads to a less P(q-1)++ He2+ + e-). In general this charged projectile and a continuum electron (Pq+ + He approximation is also valid for lower projectile velocities (1.5 a. u.), if the projectile is bare (proton, He2+). In the case of He+, where an electron originating from the projectile is involved the collision dynamics change conspicuously. We have used the COLTRIMS technology (COLd Target Recoil Ion Momentum Spectroscopy) [1] to determine the momentum vectors of all final state products to investigate the influence of the projectile electron.
References [1] J. Ullrich, R. Moshammer, A. Dorn, Drner, L. Ph. H. Schmidt and H. Schmidt-Bcking, Rep. Prog. Phys., 66, 1463 (2003)
----------------* electronic address: schoeffler@atom.uni-frankfurt.de
Collisional depolarization and polarization transfer for molecular and atomic lines. Astrophysical applications
Moncef Derouich Institut d'Astrophysique Spatiale, Batiment 121, F-91405 Orsay, France
Symmetry-breaking processes such as anisotropic radiation pumping and anisotropic collisions could create the so-called atomic polarization. This atomic polarization reflects the fact that the Zeeman sublevels of the atomic system are unevenly populated and there are quantum coherences among them. The atomic polarization leads to selective emission and/or selective absorption processes and thus to polarization in atomic/molecular spectral lines. It is important, however, not to confuse this atomic polarization with the more familiar Zeeman polarization which due to the magnetic fields. With the development of a new generation of very accurate spectro-polarimeters, the spectrum of the atomic polarization open a new window for the diagnostics of magnetic fields and physical conditions of the astrophysical mediums. The most known example is the "second solar spectrum", which is the spectrum of the linear atomic polarization observed close to the solar limb. This spectrum is as rich in spectral structures as the ordinary intensity spectrum, but is governed by different physical processes and differs in appearance and information content.To correctly interpret the spectrum of the polarization, it is necessary to know the (de)polarizing rates due to the collisions of the emitting atomic systems with nearby perturbers. In this contribution: 1) We present our collisional semi-classical theory developed over the last few years and applied for all simple/complex atoms. For solar conditions, a fundamental result which justifies our approach is that the collisional depolarization process depends strongly on the intermediate regions of collisions which are accurately described by our semiclassical approach. 2) We give the first results obtained for the collisional depolarization and polarization transfer for rovibrational levels of diatomic molecules. 3) We report a recent theoretical investigation which has been carried out in order to quantify the influence of the polarization transfer rates by collisions on the linear polarization amplitudes of several lines. 4) We establish the real contribution of the anisotropic and isotropic collisions in the polarization for the so-called multiterm atoms, i.e. where in particular the coherence between the different j-levels (the so-called superinterferences) are taken into account. We show an application of our collisional rates calculations by determining very week unresolved magnetic fields in the solar photosphere by their Hanle effect on the linear polarization of the lines. 5) Finally, we draw attention to various still open problems in the solar physics because of the luck of collisional data (e.g. MgH and C2 solar lines; Halpha line.): much important work still remains to be done and we would surely see a number of surprising results in the years to come.

Ionization of an atom in a strong laser pulse: numerical integration versus strong eld theories
Yulian V. Vanne and Alejandro Saenz AG Moderne Optik, Institut f r Physik, Humboldt-Universitt zu Berlin, u a Hausvogteiplatz 5-7, D 10117 Berlin, Germany Strong eld ionization of atoms and molecules received much attention in the past years. Various nonperturbative approaches have been proposed to describe such highly non-linear processes as multiphoton ionization, above threshold ionization or high harmonic generation. Among them, dierent variations of the Keldysh-FaisalReiss (KFR) theory (also referred to as strong-eld approximation) are often used nowadays, since they allow an analytical treatment of the problem. Although the general formulation of KFR is known for decades, there are still controversial issues, e. g., the strong gauge dependence, the possible choices for a Coulomb correction, and technical problems in the calculation of the ionization transition amplitude. We discuss two aspects related to analytical study of KFR. First is related to the method of calculating the ionization transition amplitude in length gauge KFR. Recently, it has been proposed to substitute the widely used saddle-point approximation by an exact formula based on the residue theorem. Comparing the results of both approaches for atomic hydrogen a dierence by a factor of 4 was found for the ionization rate of 1s, and an even more drastic deviation for the 2s state. We have proven [1] that this claim is incorrect, since the proposed exact Keldysh theory erroneously neglects an important term. Further, we have performed a careful analytical and numerical analysis of the quasistatic limit of the velocity-gauge KFR [2]. A simple analytical dependence on the laser frequency is found for longrange interaction potentials. The fact that the ionization rate is proportional to the laser frequency shows a break-down of velocity-gauge KFR in the quasistatic limit. The Coulomb correction proposed by A. Becker et al. [3] does not remove this problem. Based on the Perelomov-Popov-Terentev tunneling formula [4] we derive a Coulomb correction factor for velocity-gauge KFR in the weak eld limit. Based on a full numerical integration of the time-dependent Schrdinger equation o we have performed a systematic test of dierent variants of KFR theory in a wide range of laser parameters like peak intensities, pulse lengths and frequencies. [1] Y. V. Vanne and A. Saenz, Phys. Rev. A (2007) in press; arXiv:physics/0610032. [2] Y. V. Vanne and A. Saenz, submitted to Phys. Rev. A; arXiv:physics/0701295. [3] A. Becker et al., Phys. Rev. A 64, 023408 (2001). [4] A. M. Perelomov et al., Sov. Phys. JETP 23, 924 (1966).

ULTRAFAST PHOTOPROCESSES IN CONTACT ION PAIRS OF INDOTRICARBOCYANINE DYES
Tikhomirov S.A., 1Samtsov M.P., 2Dubovskii, V.L., Buganov O.V., Melnikov D.G., Voropay E.S.
A.N.Sevchenko Research Institute for Applied Physical Problems of the Belarusian State University, Minsk, Belarus 2 Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, Ave. Nezalezhnasti 70, 220072 Minsk, Belarus E-mail: tikhomirov@imaph.bas-net.by
Cationic polymethine dyes have considerable promise as photosensitizers for photochemotherapy of cancer and as biological markers for various applications. As demonstrated in [1,2], indotricabocyanine dyes are localized in tumor cells within the region characterized by a low dielectric constant, mainly in the form of contact ion pairs. Proceeding from the fact that indotricarbocyanine dyes retain their photocytotoxicity in hypoxic conditions [2], the charge transfer in contact pairs with the formation of free radicals may be thought as a starting mechanism for the tumor cell damage. However, in literature one can find conflicting opinions concerning a possibility of the photochemical reactions proceeding with the electron phototransfer in contact ion pairs of polymethine dyes and simple "inert" ions (e.g., Br-, lO4-). This communication presents the recent experimental results obtained in studies into the spectroscopic properties of a series of indotricarbocyanine dyes in solvents of different nature. The principal objective of the work is to investigate fast relaxation processes taking place in the molecules under study just after their excitation and to analyze the possibility for the realization of fast direct and back charge transfer in ion pairs of indotricarbocyanine dyes with simple Br-, I- and ClO4- anions. A comparative analysis of the femtosecond transient absorption spectra recorded for these compounds in conditions enabling transition of the dye molecules into the excited state in a specific ionic form is performed. The experiments and measurements of transient absorption spectra of the dyes conducted using a home-made femtosecond spectrometer [3], based on the original Ti: Sp generator with synchronous pumping by a Nd: YAG pulsed laser and a regenerative amplifier, are described. Fast transformations (ps) of transient absorption spectra in a long wavelength absorption band of the compounds studied are interpreted within the framework of the concept of a hole burning at the profile of a vibronic band. The qualitative differences in registered absorption spectra from the excited electronic states of the molecules studied at different experimental conditions are explained assuming ultrafast charge transfer in contact ion pairs that results in the formation of free radicals. [1] E.S. Voropay, M.P. Samtsov, K.N. Kaplevsky, A. A. Lugovskiy, J. Appl. Spectroscopy, 71, 168 (2004). [2] Y.P. Istomin, E.N. Alexandrova, E.A. Zhavrid, E.S. Voropay, M.P. Samtsov, e.a., Experim. Oncology, 28, 80 (2006). [3] A.P. Blokhin, M. F. Gelin, O.V. Buganov, S.A. Tikhomirov, G.B. Tolstorozhev, J. Appl. Spectroscopy, 70, 66 (2003).

1E-005 0E+000

c1=1.0 c2=1.28

0.3 0.25 0.2 0.15 0.1 0.05
-1E-005 -2E-005 -3E-005 720
c3=1.57 c4=1.86 c5=2.15 c6=2.44 c7=2.72

Wavelength [nm]

Concentration % v/v
Figure 1. Relative change of spectral refraction index (a) and dispersion (b) of bacteriorhodopsin at different concentrations.
References [1] C.P.Zhang, Q.W.Song, C.Y.Ku, R.B.Gross, R.R.Birge, Opt.Lett. 19, 1409 (1994) [2] A.P. Kovacs, K. Osvay, Z. Bor, R. Szip cs, Opt.Lett., 20, 788 (1995)
The backbone effects in intermolecular normal mode vibrations of adenine-thymine simple and double sequenced base pairs system
A. Bende1,2 and S. Suhai2
National Institute for R&D of Isotopic and Molecular Technologies, Molecular and Biomolecular Physics Department, Donath Street, No 71-103, Ro-400293, Cluj-Napoca, Romania. email: bende@s3.itim-cj.ro German Cancer Research Centre, Molecular Biophysics Department, Im Neuenheimer Feld 580, D-69120, Heidelberg, Germany. email: S.Suhai@dkfzheidelberg.de
Hydrogen bonding is ubiquitous in nature and governs a wide array of chemical and biological processes ranging from local structure in molecular liquids to the structure and folding dynamics of proteins. Although the hydrogen bond is well studied, its low-frequency vibrations - the large-amplitude motions involving stretching and bending along the actual hydrogen-bond coordinates - have been rarely investigated. Information about these vibrations offers exceptional insight into the potential energy surface of the interaction and so further enhances our understanding of the hydrogen bond and its impact on molecular structure and dynamics. The "C=OH-N" type hydrogen-bond (HB) is the one of the most frequent occur rent Van der Waals (VdW) bond in the biological systems. They can be found as a main component of the DNA bases pairs interaction systems or in protein -helix and sheets. In their cases, not only the cognition of molecular structures are so much important, but also their dynamics, which in essence represent their biological functionality. In our previous work we have investigated the nature of this C=OH-N hydrogen bond in case of formamide-water and formamide-formamide systems [1], giving a detailed description for binding energies, inter and intramolecular harmonic frequencies and their anharmonic corrections. The equilibrium structures, binding energies and vibrational harmonic frequencies of the simple and double sequenced adenine-thymine (AT) molecular structures including the sugar-phosphate backbone has been investigated in order to study the low-frequency IR spectra using B3LYP exchange-correlation potential and considering the D95* basis set. The widely used a posteriori Boys-Bernardi "counterpoise" (CP) correction scheme for basis set superposition error (BSSE) elimination, has been included in our calculations in order to take into account the BSSE effects in geometry optimisation, binding energies and the harmonic vibrational frequencies. The different intermolecular normal mode vibrations of the simple and double sequenced AT-backbone molecular systems has been compared with the classical backbone-free AT system and the change in their normal mode vibrational behaviour are discussed. References [1] A. Bende and S. Suhai, Int. J. Quantum Chem., 103(6), 841 (2005).

Figure 1 Yields of the various deoxyribose fragments following 20 keV He+ impact
For a subset of collision events, where he initial and final states of the projectile are well defined (e.g. H+ + adenine (adenine2+)* + H-), it is possible to use coincidence techniques to determine the amount of energy transferred to the molecule during the interaction process for the different fragmentation channels. This data is used to interpret the slope of the above mentioned power-law. [1] Z. W. Deng, I. Bald, E. Illenberger and M. A. Huels, Phys. Rev. Lett., 2005, 95, 153201 [2] J. de Vries, R. Hoekstra, R. Morgenstern and T. Schlathlter, Phys. Rev. Lett. 91 (2003) 053401 [3] F. Alvarado, S. Bari, R. Hoekstra, T. Schlathlter, Phys. Chem. Chem. Phys. 8, (2006) 1922
ELECTRON INDUCED CAPTURE DISSOCIATION OF PEPTIDE CATIONS.
Anne I. S. Holm, Preben Hvelplund, Umesh Kadhane, Steen Brndsted Nielsen, Subhasis Panja, Kristian Stchkel and Esben S. Worm Department of Physics and Astronomy, University of Aarhus, Denmark Mass spectrometry is used successfully to elucidate the primary structure of peptides and proteins, that is, the sequence of amino acids. The standard method is to induce fragmentation by collisions but the often very rich fragmentation spectra can be a disadvantage as too many peaks may complicate assignments. This problem has more or less been overcome with the technique electron capture dissociation (ECD), which is based on the capture of low-energy electrons by ions in the cell of a Fourier transform ion cyclotron resonance instrument. The advantage of ECD is that it leads to breakage of specific bonds in the peptide chain. Here I will show how we in Aarhus mimic the ECD process by transfer of an electron from an alkali metal atom to a peptide dication of high translational energy. Recent experimental results from our group shed light on the mechanism behind ECD.
Quantum Mechanical Self-Assembling of Artificial Minimal Cells and Control by Molecular Electronics and Spintronics Logical Devices Arvydas Tamulis and Vykintas Tamulis Institute of Theoretical Physics and Astronomy of Vilnius University, A. Gotauto 12, Vilnius, Lithuania We used quantum mechanical (QM) electron correlation density functional theory (DFT) methods, i.e. done exact quantum mechanical experiments to investigate various self-assembled photoactive bioorganic systems of artificial minimal cells based on peptide nucleic acid (PNA) consisting of up to 800 atoms and 5 nm in diameter [1-2]. The electron correlation hydrogen bonds and Van der Waals interactions that result from the addition of water (or methanol) and fatty acid (FA) molecules play the critical role in quantum self-assembly of photosynthetic center and functioning of the photosynthetic processes in artificial minimal cells. The distances between the separated sensitizer, fatty acid precursor (pFA) and water molecules are comparable to Van der Waals and hydrogen bonding radii and therefore these nonlinear quantum interactions compress the overall system resulting in a smaller gap between the HOMO - LUMO and photoexcited electron tunneling from sensitizer (1,4-bis(N,N-dimethylamino)naphthalene or Ru(bipyridine)32+) to pFA molecules which is calculated by time dependent density functional theory (TD DFT) method and differs from spectroscopic experiments only by 0.2 nm (in the value of experiment errors) that means what quantum mechanical selfassembled structures of minimal cells are very close in comparison to the realistic ones in the nature. QM electron correlation experiments of self-assembly of artificial minimal cells show that these cells are complex systems because only entire ensembl of PNA, sensitizer, pFA, FA and water molecules is stable and perform quantum photosynthetic processes. Removing the small part of nucleobase, FA and water molecules leads to the structural changes in comparison with realistic structures and difference in comparison with the spectroscopic values of photoexcited electron tunneling from sensitizer (1,4-bis(N,N-dimethylamino) naphthalene or Ru(bipyridine)32+) to pFA molecules. QM electron correlation experiments of self-assembly of artificial minimal cells removing the main part of nucleobase, FA and water molecules leads to the degradation of these cells [2]. We can state what the inclusion of ever more water, fatty acid and nucleobase molecules in the different artificial minimal cells results in a shift of the absorption spectrum to the red for the artificial protocell photosynthetic centre, leading to an ever closer approach to the real experimental value and indicates the measure of the complexity of this quantum complex system, i.e. a minimal protocell. It is important to say that only QM electron correlation TD-DFT experiments with minimal protocells gives results exactly comparible with spectroscopic results and all other more simplyfied QM methods such as local gradient DFTor ab initio Hartree-Fock gives structures and spectra far from the experimentally measured. Implementation of quantum information bits based on spatially localized electron spins in stable molecular radicals are investigated by unrestricted DFT methods installed in the Gaussian03 package [3, 4]. The DALTON package is used for the g-tensor shift calculations of neutral radical molecules: -diketone and syringate. -diketone neutral radical moiety with an attached hydrocarbon chain is suitable for construction of quantum computing processing devices because the qubit is relatively stable due to the small magnitude of gtensor shift component that is aligned with the external magnetic field, i.e. the direction of hydrocarbon chain which provide the self-assembled monolayer an attachment of the molecule to a substrate. TD-DFT simulations of the artificial minimal cells with implemented molecular electronics and spintronics gates done using self-assembled neutral radical molecules -diketone and syringate show that it is possible to construct more general ContrlNOT and NAND logic functions suitable for the production of the nanobiorobots. Results of our detailed investigations provides a collection of quantum mechanical tools including

References [1] D. G. Fried et al., Phys. Rev. Lett. 81, 3811 (1998) [2] S. Vasilyev et al., Phys. Rev. A. 69, 023610 (2004) [3] J. Ahokas et al., Phys. Rev. Lett. 98, 043004 (2007) and references therein.
TRAPPING AND GUIDING ULTRACOLD ATOMS WITH THE HELP OF QUANTUM REFLECTION
Javier Madro ero1 , Florian Arnecke and Harald Friedrich n Physik Department, Technische Universitt M nchen, 85747 Garching, Germany a u Understanding the interaction of ultracold atoms with surfaces is a prerequisite for the design and construction of atomic waveguides and other atom-optical devices. The interaction in the close regime, i.e. when the atom is separated from the surface by few atomic units, is quite complicated and generally leads to inelastic reactions or adsorbtion. Beyond this close region the solid surfaces provide a longrange attractive potential for the atoms. For distances shorter than the wavelength of atomic transitions the interaction is the van der Waals potential, while at larger distances the retardation eects become important. At suciently low energies, atom-surface collisions are strongly inuenced by quantum eects such as quantum reection in the nonclassical region of an attractive atom-surface potential and dominance of low partial waves in the elastic scattering by nanospheres [1,2]. We discuss the possibilities of 1 exploiting quantum reection to 0.8 trap atoms without the help of auxiliary elds. Accurate numer0.6 ical calculations taking into ac0.4 count the long-distance retarded potential and the short distance 0.2 van der Waals potential [3] show 0.2 0.4 0.6 0.that the behavior of the trapped atoms between two walls can be The surviving fraction of trapped atoms (solid successfully modeled by an apline) can be successfully reproduced by a simplipropriate sharp-step potential [4]. ed step potential approximation (dotted line). An extension of this model to Quantum reection reduces the decay process higher dimensions allows us to and signicantly enhances the survival probabilstudy the conning properties of ity in comparison with the free evolution (dotatoms in traps of more complidashed line). cated geometries [5]. We show that quantum reection makes it possible to achieve a good suppression of the decay process of atoms conned in traps of dierent geometries. Under realistic conditions quantum reection can enhance the survival probability by up to two orders of magnitude in a three dimensional trap or by a factor 15 in atomic wave guides. References [1] [2] [3] [4] [5] F. Arnecke, H. Friedrich and J. Madro ero, Phys. Rev. A 74, 062702 (2006) n F. Arnecke, H. Friedrich and J. Madro ero, Submitted to Phys. Rev. A. n J. Madroero and H. Friedrich, Accepted in Phys. Rev. A. n A. Jurisch and H. Friedrich, Phys. Lett. A 349, 230 (2006) J. Madroero and H. Friedrich, Submitted to Phys. Rev. A. n

In the region close to the double-ionization threshold helium approaches the semiclassical limit, i.e. the effective tends to 0. Since the classical counterpart of the helium atom, the three-body Coulomb system, is non-integrable and exhibits a mixed phase space, quantum chaos is expected in this region of doubly excited resonances. Studies of these resonances below the single ionization threshold (SIT) I9 of He+ showed a transition towards quantum chaos by analyzing the distribution of the nearest-neighbor energy spacings (NNS) between the resonances [1]. Now we present the experimental total photoionization cross section up to the SIT I15, together with state-of-the-art complex-rotation calculations revealing an excellent agreement. Based on the calculations the spectral features were assigned using the classification scheme N,Kn, with N (n) being the principal quantum number of the inner (outer) electron and K the angular-correlation quantum number. The quantum number K represents the expectation value for the angle defined by the electrons and the nucleus and can vary from K=N-1 to K=-(N-1). The values of K close to the maximal and minimal value can be related to 1-dimensional helium with both electron being on different site (eZe-configuration) or on the same site of the nucleus (Zeeconfiguration), respectively. We studied the validity of the approximate quantum numbers N and K by investigating the statistical properties of the NNS. These studies proved that for the resonances with K close to N-1 the quantity F = N - K is a good quantum number. However, a separate consideration of N and K shows a NNS distribution typical for a chaotic system and indicates that the principal (radial) quantum number N already lost its physical meaning below SIT I15. For the resonances with K close to -(N-1) we found that K and N are separately good quantum number. The behavior of the quantum numbers can be understood on the basis of classical 1-dimensional helium since the Zee-configuration is known to be stable with respect to perturbations in angular and radial direction, while the eZe configuration is only stable with respect to perturbations in angular direction. The existence of good quantum numbers for part of the resonances below SIT I14 show that the transition region from integrability to full chaos is much larger than previously assumed. Since F turned out to be a good quantum number for the resonances with K close to N-1, the cross section can be described with a small number of only partially overlapping resonances, i.e. we found up to I15 no evidence for Ericson fluctuations, which are considered to be an additional signature of quantum chaos.

angular

EINSTEIN COEFFICIENTS FOR ACTIVATION BARRIER
Anatoly V. Stepanov National Ozone Monitoring Research and Educational Centre, Byelorussian State University, Minsk 220064, Belarus
Analytical calculation of Einstein coefficients is made for activation barrier of the BoltzmannArrhenius model and an activation process model. For the activation process model an activation barrier is shown to have discrete energy structure due to its thermodynamic equilibrium with thermal radiation. This structure is determined by interaction of conformation substates of a molecule with thermal radiation. The BoltzmannArrhenius model represents an activation process as a result of the work of high-energy spectral components of thermal equilibrium radiation. The process is realized by overcoming a potential barrier with continuous energy structure. However, it is shown, that such process is essentially non-equilibrium and hard to achieve at thermal equilibrium radiation [1].
References [1] http://dx.doi.org/10.1016/j.theochem.2006.10.021
Loschmidt echo in a system of interacting electrons
G. Manfredi and P.-A. Hervieux Institut de Physique et Chimie des Matriaux de Strasbourg, GONLO, 23 rue du Loess, 67034 Strasbourg, France
In a famous controversy with Ludwig Boltzmann at the dawn of modern statistical mechanics, Joseph Loschmidt pointed out that, if one reverses the velocities of all particles in a physical system, the latter would evolve back to its initial state, thus violating the second law of thermodynamics. The main objection to this line of reasoning is that velocity reversal is an extremely unstable operation and that tiny errors would quickly restore normal entropy increase. Nevertheless, time reversal is indeed possible, as was shown in spin echo experiments performed since the 1950s. Loschmidts idea has recently experienced a resurgence of interest in the context of quantum information theory. Indeed, any attempt at coding information using quantum bits is prone to failure if a small coupling to the environment destroys the unitary evolution of the wave function (decoherence). In order to estimate the robustness of a physical system, the following procedure has been suggested: a single quantum particle evolves under the action of a chaotic Hamiltonian H0 until a time T; then, it is evolved backwards in time until 2T with the original Hamiltonian plus a small perturbation (the environment). The square of the scalar product of the initial and final states defines the Loschmidt echo or fidelity of the system. Theoretical and numerical studies showed that the Loschmidt echo decays exponentially with the time delay T. What happens when one deals, not with a single particle, but with a large system of interacting particles, such as the electrons in a metallic or semiconductor nanostructure? In order to answer this question, we devised a quantum hydrodynamic model that includes electron-electron interactions via the self-consistent Coulomb field. The results of our numerical experiments were intriguing: the fidelity does not decay exponentially, but rather stays close to unity until a critical time, after which it drops abruptly (see figure). This unusual behaviour is related to the fact that the unperturbed Hamiltonian H0 depends on the electron density ne. When the perturbation induces a small change in ne, H0 is itself modified, which in turns affects ne, and so on. Thanks to this snowball effect, the perturbed and unperturbed solutions can diverge very fast. This effect could be a generic feature of interacting many-particle systems. If so, it would have an impact on the decoherence properties of solid-state quantum computation devices, which may then behave differently in the single-electron and many-electron regimes.

1.S. i l N M khaienko,A. be,V lG. Bar. Tyut ev,A. cher A t os O cean.O pt 12,771 ( er Chi y, m. 1999) 2. V lG.Tyut ev , At os O cean. ptcs ,16 ,pp 220- (. er m. O i 230 2003) 116, 2002) 3.R.Si t P. eur - s d,R.Schi eber, Fl atLes ar nke,M.Bit er ter ova,S. Far os JCP, 9749( C. ant , 4.H. enz,W. em toeder J. aud ,J M olSpect. 209,267( W D r , M Fl. r, 2001) 5.A. Cam par gue,S. as i D. K s , Rom ani ,A. be,. D e Backer Barly,V lG. ni Bar M R. - il. Tyut ev,JM S,240, er 113 ( 2006)( r er and ef ences t ei her n) 5 Vl G. Tyut ev,S.Tas er A hkun,D.Schw enke, P.J en ,T.Cour , A.Bar and M.Jacon, W ens s be Chem.Phys Let ,316,271- (. t ). 6.V lG.Tyut ev,S.A.Tas. er hkun,H. Seghi, SPI ,I s N 5311, pp164r E s ue 175 ( 2003)
PHOTODISSOCIATION OF ALKALI DIMER MOLECULES AND DIATOMIC BUBBLES IN SOLID 4HE
P. Moroshkin, A. Hofer, and A. Weis Physics Department, University of Fribourg, Switzerland
We present experimental and theoretical studies of laser photodissociation of cesium dimers isolated in a solid 4He matrix. The dissociation products (excited Cs atoms and Cs*HeN exciplexes) are detected via their spectrally and time-resolved fluorescence. We have found several new features of this emission as compared to that of laser-excited Cs atoms in solid He under the same conditions [1]: (i) a reduced spectral shift of the 6P1/2 6S1/2 (D1) fluorescence, (ii) the appearance of 6P3/2 6S1/2 (D2) fluorescence which is otherwise completely quenched, (iii) a shortening of the lifetime of the excited 6P1/2 state (partial quenching). It is well known that alkali atoms in condensed helium reside in small cavities called atomic bubbles [1]. We attribute the new features to a different trapping site structure: a diatomic bubble that contains one excited and one ground-state Cs atom or one Cs2 molecule with a large internuclear separation. The excess kinetic energy of the dissociation products is transferred to surrounding He atoms and dissipated in the crystal. Our analysis of Cs-Cs and Cs-He interactions shows that the observed effect is not due to a C6/R6 van der Waals interaction between two Cs atoms, residing each in its own bubble, but that it can be explained if the two atoms represent a molecule bound by a long-range C3/R3 dispersion interaction [2]. In the latter case each of the two Cs atoms is in a 50:50 coherent superposition of the 6P and 6S states. Any bubble deformation that is not symmetric with respect to a reflection in a plane separating the Cs atoms, should result in a collapse of the diatomic wavefunction into one 6P and one 6S atom. From the measured decay times of the D1 and D2 fluorescence we conclude that this happens on a time scale of several nanoseconds and that the bubble distortion responsible for this quenching is in fact the formation of a Cs*HeN exciplex. References [1] P. Moroshkin, A. Hofer, S. Ulzega, A. Weis, Low Temp. Phys. 32, 981 (2006) [2] K. M. Jones, E. Tiesinga, P. D. Lett, P. S. Julienne, Rev. Mod. Phys., 78, 483 (2006) 712