The interaction of water vapor with ice remains incompletely understood despite its importance in environmental processes. A particular concern is the probability for accommodation on surface, which results from earlier studies vary by more than 2 orders magnitude. Here, we apply an molecular beam method to directly determine and desorption kinetics ice. Short D2O gas pulses collide H2O between 170 200 K, a fraction adsorbed molecules desorbs within tens milliseconds first order kinetics....

The apparatus for a coupled 3D wave-packet solution of the reactive three particle scattering problem is given. method uses hyperspherical coordinates with hyperradius and two hyperangles propagated as wave packet. coupling these packets arises through rotation plane by Euler angles. necessary formulas transformation to Cartesian projection on asymptotic states are also

The dissociative recombination (DR) process of NH4+ and ND4+ molecular ions with free electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). absolute cross sections for DR in collision energy range 0.001–1 eV are reported, thermal rate coefficients temperature interval from 10 to 2000 K calculated experimental data. section agrees well earlier work is about a factor 2 larger than ND4+. dominated by product channels NH3+H...

A recently developed scheme for time-dependent reactive scattering calculations using three-dimensional wave packets is applied to the D+H2 system. The present method an extension of a previously published semiclassical formulation problem and based on use hyperspherical coordinates. convergence requirements are investigated by detailed total angular momentum J equal zero general applicability demonstrated solving J=1 problem. inclusion geometric phase also discussed its effect reaction...

Thermal rate coefficients for the reactions C(3P) + NO(X2Π) → CN(X2Σ+) O(3P), CO(X1Σ+) N(2D), and O(3P) N(2D) in temperature range from 5 to 5000 K have been obtained using quasiclassical trajectory calculations. Results are reported two ab initio potential energy surfaces corresponding states of 2A' ' symmetry. Good agreement between calculated experimental C NO all temperatures, whereas coefficient O CN reaction at room is larger than that found experimentally. The dynamics considerably...

We present classical trajectory calculations of ArnNem (n+m=111, 859) clusters scattering from a rigid surface. The dynamics energy transfer and cluster decomposition during surface is investigated for incident velocities 100–700 m/s. initial translational at impact effectively transferred into internal degrees freedom the cluster. overall efficiency very high but not complete, leaving too much in translation. No fragmentation takes place below 200 At 450 m/s, evaporation small fragments...

The title reaction is investigated for total angular momentum ℐ=0 using a semiclassical coupled wave packet method where the Smith–Whitten-type hyperspherical angles θ and φ are treated quantally, radius ρ classically. function expanded over an electronic basis set which includes 28 states. diabatic potential energy surfaces determined by DIMZO calculations. Probabilities reaction, charge transfer, collision induced dissociation, dissociative fine structure transitions obtained in range 0.3...

Classical trajectory calculations of (H2O)n+(H2O)n collisions are carried out for n=125 and n=1000. We investigate energy redistribution fragmentation behavior relative collision velocities up to 3000 ms−1, impact parameters 4 nm, initial cluster temperatures 160 300 K. Three main scattering channels identified; coalescence, stretching separation, shattering collisions. For small parameters, low produce coalesced clusters while high yield behavior. Large combined with result in separation A...

Formation of water/ice layers on graphite has been studied in the temperature range from 90 to 180 K by elastic helium scattering, light and molecular dynamics simulations. Combined helium- light-scattering experiments show that an ice film wets surface is formed at temperatures 100−140 K, whereas three-dimensional structures are 140−180 K. Desorption adsorbed water molecules competes with incorporation into film, formation rate strongly dependent. At 150 ice-layer takes place same time...

Environmental molecular beam experiments are used to examine water interactions with liquid methanol films at temperatures from 170 K 190 K. We find that molecules 0.32 eV incident kinetic energy efficiently trapped by the methanol. The scattering process is characterized an efficient loss of surface modes a minor component inelastically scattered. Thermal desorption has well Arrhenius form activation 0.47{\pm}0.11 and pre-exponential factor 4.6 {\times} 10^(15{\pm}3) s^(-1). also observe...

We report on molecular beam experiments and dynamics simulations of xenon scattering with incident energies E=0.06−5.65 eV from graphite. The corrugation felt by an atom interacting the surface is found to be influenced both temperature, Ts, E. Angular distributions are significantly broadened when Ts increased, clearly indicating induced thermal motion also at highest E employed. Direct dominates for high E, while trapping becomes important kinetic below 1 eV. coupling between translation...

3D wave packet calculations on the CH2I2 and OClO molecules have been performed for a total angular momentum equal to zero. The initial function is found by solving time independent Schrödinger equation in internal bond coordinates. split operator method fast Fourier transform hyperspherical coordinates are used order follow quantum dynamics. An absorption spectrum of obtained compared with previous 2D calculation. A Raman molecule at 355 nm calculated experimental results. X2B1→A2 A2...

Vibrational relaxation cross sections and rate constants of HF(v=1) by Ar are calculated on a recent semiempirical potential energy surface (PES) [J. Chem. Phys. 111, 2470 (1999)] using the quantum-mechanical coupled states approach. Accurate theoretical estimations coefficients for vibrational at temperatures between 100 350 K obtained. The is shown to be quasiresonant character occur mostly two nearest rotational levels ground state. weak isotope effect after substitution HF DF...

A recent theoretical study of the ion–dipole capture process using classical variational and effective potential methods is extended to quantum regime. Capture rate coefficients are calculated for energy surface utilizing a model where vibrations frozen, rotations quantized translational motion classical. Results from simple adiabatic theory, transition state an method presented compared with corresponding results trajectory calculations H+3 ions colliding HCl, HCN, CS. Comparison also made...

Dissociative recombination (DR) of water cluster ions H+(H2O)n (n=4–6) with free electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). For first time, branching ratios have determined for dominating product channels and absolute DR cross sections measured in energy range from 0.001to0.7eV. is concluded to result extensive fragmentation all three ions, a maximum number heavy oxygen-containing fragments produced probability close...

Dissociative recombination (DR) of the water cluster ions H+(H2O)3 and D+(D2O)3 with electrons has been studied at heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). For first time, absolute DR cross sections have measured for in energy range 0.001–0.8eV, relative 0.001–1.0eV. The are larger than previously observed H+(H2O)n (n=1,2), which is agreement trend indicating that rate coefficient increases size ion. Branching ratios determined dominating product...

Water interactions with organic surfaces are of central importance in biological systems and many Earth system processes. Here we describe experimental studies water collisions uptake kinetics on liquid solid butanol from 160 to 200 K. Hyperthermal D2O molecules (0.32 eV) undergo efficient trapping both butanol, only a minor fraction scatters inelastically after an 80% loss kinetic energy surface modes. Trapped either desorb within few ms, or taken up by the phase during longer times. The...

Abstract. Molecular scattering experiments are used to investigate water interactions with methanol and n-butanol covered ice between 155 K 200 K. The inelastically scattered desorbed products of an incident molecular beam measured analyzed illuminate scale processes. residence time uptake coefficients impinging on alcohol-covered calculated. surfactant molecules observed affect transport from the surface in a manner that is related number carbon atoms they contain. Butanol films reduce by...