Energy distribution in aniline scattered from various low energy surfaces

Abstract

Aniline has been scattered from three organic substrates and a LiF single crystal surface. Applying multiphoton ionization and time of flight measurements the vibrational, rotational, and translational energy distributions were measured simultaneously. The NH2 ‘‘umbrella’’ like mode was found to be a very efficient accepting mode in the energy transfer process. The less rigid the surface, the greater the efficiency with which this mode is populated. The mode specificity does not exist for the rigid LiF surface. A model is presented, which explains all observations based on the collision time and kinematics.

Energy transfer in rare gas collisions with hydroxyl- and methyl-terminated self-assembled monolayers

“…Sagiv and Naaman have speculated that end-group rotation, as well as concerted waving motion, controls the energy transfer dynamics in collisions of atomic gases from amphilic organic monolayers. 11,12 In the studies presented here, the CH 3 -T surface has additional or slightly different energy modes, relative to the OH-T surface, into which the kinetic energy of the impinging particle can be partitioned. The CH 3 torsional mode ͑ϳ2 kJ/mol͒, as well as the stretching ͑ϳ37 kJ/mol͒ and deformation modes ͑ϳ15 kJ/mol͒, are well within the energy range of the impinging Ar atoms ͑80 kJ/mol͒.…”

“…4 -10 In addition, the mass of the molecules used to create a monolayer has been shown to have a marked influence on the gas-surface energy transfer dynamics. 11,12 The ability to create SAMs with a wide variety of chemical functionalities enables one to extend this work to learn how the chemical nature of the interface influences energy transfer dynamics in the initial gas-surface collision. For example, intramonolayer hydrogen bonding may add structural rigidity to a monolayercovered surface thereby hindering translational-tovibrational energy transfer.…”

“…The monolayercovered surface should provide several additional degreesof-freedom into which the translational energy of the atom can be partitioned. 11,12 The concerted waving motions of the chains, vibrational modes along the chains, and hindered rotations of the end groups can all be excited by the 80 kJ/mol incident Ar atoms. Furthermore, kinematic arguments predict that energy transfer increases as the mass of the surface decreases.…”

“…Furthermore, kinematic arguments predict that energy transfer increases as the mass of the surface decreases. 11,12,21,22 It would take approximately 13 methyl groups, mϭ15 amu, to equal the mass of one Au atom, m ϭ197 amu. As shown in Fig.…”

Classical trajectory study of collisions of Ar with alkanethiolate self-assembled monolayers: Potential-energy surface effects on dynamics

“…Noble gases are ideal candidates to investigate how energy flows among various degrees of freedom in gas/surface collisions because their inert nature precludes chemical reactions with the surface. [7][8][9][10][11][12][13][14][15] In contrast with the gas-phase experiments, the gas/surface experiments measure T → INTЈ energy transfer, where INTЈ refers to the internal degrees of freedom of the surface. 1,2 More recently, the use of supersonic molecular beams has enabled characterization of inelastic energy transfer in collisions of fast noble-gas atoms with organic surfaces.…”