Rotationally mediated vibration–vibration and vibration–translation energy transfer in silane

Abstract

Vibration–vibration (V–V) and vibration–translation (V–T) energy transfer efficiencies have been measured for the v4=1 mode of silane in collisions with He, Ar, Kr, H2, CH4, and itself, using the time-resolved infrared double-resonance technique. The V–V cross sections are approximately one-third to one-half of the Lennard-Jones cross sections, and show a variation with the nuclear–spin symmetry state (A, E, or F) of the molecule. The ν4 V–T deactivation efficiencies are in the range 0.0001–0.002, with the polyatomic molecules being about an order of magnitude more efficient than the noble-gas atoms. This can be quantitatively interpreted by the vibration–rotation (V–R) resonance transfer model of Poulsen et al. [J. Chem. Phys. 58, 3381 (1973)]. A simple breathing-sphere model does not, however, provide a good representation of the V–T collision efficiencies for rare gas–silane collisions.

State-to-State, Rotational Energy-Transfer Dynamics in Crossed Supersonic Jets: A High-Resolution IR Absorption Method

“…Typically, a target molecule in a gas cell is prepared in a single v , J state with a pulsed laser. − Alternatively, a nonthermal distribution of initial states is created via laser photolysis, fast chemical reactions, or collisions with a translationally energetic atom. − As the target molecules approach thermal equilibrium via collisions with a bath gas, the time evolution of the rotational state distribution is monitored with detection techniques such as infrared chemiluminescence, time-resolved Fourier transform spectroscopy, , pulsed laser-induced fluorescence, , or infrared laser absorption spectroscopy. ,, The state-to-state cross sections, averaged over a spread in thermal velocity, can be inferred through detailed kinetic models of the time-dependent populations in each J state. These bath gas relaxation techniques have been used in determinations of state-to-state, rotational energy transfer cross sections for collision systems such as HF with rare gases, CH 4 + CH 4 , ,− CO 2 with translationally hot H atoms, O( 1 D), and electronically excited Br*( 2 P 1/2 ), , self-relaxation in D 2 CO, N 2 , and H 2 and in the open-shell radical systems OH + rare gases, N 2 , and O 2 . By comparison of calculated and experimentally determined rotational energy transfer cross sections and their kinetic energy dependencies, the accuracy of ab initio and empirical potential energy surfaces can be tested for a number of simple atom + molecule collision systems. − ,, …”

“…20 Typically, a target molecule in a gas cell is prepared in a single V, J state with a pulsed laser. [21][22][23][24][25][26][27] Alternatively, a nonthermal distribution of initial states is created via laser photolysis, 28 fast chemical reactions, 29 or collisions with a translationally energetic atom. [30][31][32] As the target molecules approach thermal equilibrium via collisions with a bath gas, the time evolution of the rotational state distribution is monitored with detection techniques such as infrared chemiluminescence, 29 time-resolved Fourier transform spectroscopy, 28,32 pulsed laser-induced fluorescence, 24,33 or infrared laser absorption spectroscopy.…”

“…30,31,34 The state-to-state cross sections, averaged over a spread in thermal velocity, can be inferred through detailed kinetic models of the time-dependent populations in each J state. These bath gas relaxation techniques have been used in determinations of state-to-state, rotational energy transfer cross sections for collision systems such as HF with rare gases, 34 CH 4 + CH 4 , 21,[25][26][27] CO 2 with translationally hot H atoms, O( 1 D), and electronically excited Br*( 2 P 1/2 ), 30,31 selfrelaxation in D 2 CO, 35 N 2 , 36 and H 2 37 and in the open-shell radical systems OH + rare gases, N 2 , and O 2 . 33 By comparison of calculated and experimentally determined rotational energy transfer cross sections and their kinetic energy dependencies, the accuracy of ab initio and empirical potential energy surfaces can be tested for a number of simple atom + molecule collision systems.…”

Calculation of (100)↔(001) Coriolis-Assisted Transfer Rates for O3 – N2 and O3 – O3 Collisions

“…D2CD [1][2][3][4], CD3H [5], CD4 (6], CD3CI [7], SiH4 (8] and 03 [9][10][11]. by pumping 03 molecules into a (100) rotational level and monitoring the ensuing population increase of a selected (001) rotational level [9][10][11].…”