Non-sticking of helium buffer gas to hydrocarbons

Abstract

Lifetimes of complexes formed during helium-hydrocarbon collisions at low temperature are estimated for symmetric-top hydrocarbons. The lifetimes are obtained using a density-of-states approach. In general the lifetimes are less than 10-100 ns and are found to decrease with increasing hydrocarbon size. This suggests that clustering will not limit precision spectroscopy in helium-buffer-gas experiments. Lifetimes are computed for noble-gas benzene collisions and are found to be in reasonable agreement with lifetimes obtained from classical trajectories as reported by J.

Long-lived complexes and signatures of chaos in ultracold K2 +Rb collisions

“…It is possible that numerically exact quantum scattering calculations including all the effects omitted in these calculation will never be computationally tractable. As such statistical approaches offer an alternative way to attack such problems [20,21,24,51].…”

Interactions of benzene, naphthalene, and azulene with alkali-metal and alkaline-earth-metal atoms for ultracold studies

“…[30][31][32][33] ) but just a few works have considered larger molecules [34][35][36][37][38] and experimentally only ammonia molecules were immersed into ultracold rubidium atoms 39 . Cold collisions and sympathetic cooling of molecules as large as benzene were theoretically investigated only for mixtures with helium and other rare-gas atoms [40][41][42][43][44][45] . Intermolecular interactions of benzene and naphthalene with raregas atoms were investigated theoretically and experimentally [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] .…”

Rotational Cooling Effect on the Rate Constant in the CH3F + Ca+ Reaction at Low Collision Energies

“…Since the typical inlet pressure of a helium buffer gas was set to about 80 Pa, the number of elastic collisions between a fluoromethane molecule and a helium atom is estimated to be at least 90 at 30 K from the conductance calculations of the buffer-gas line. Thus, we expected that the polar molecules in the cold gas cell were sufficiently rotationally cooled by the helium buffer gas, which has the wall temperature owing to thermal equilibrium. , The detail of the calculations is described in Supporting Information. The exit aperture was positioned closely at the input of the wavy Stark velocity filter.…”

“…Thus, we expected that the polar molecules in the cold gas cell were sufficiently rotationally cooled by the helium buffer gas, which has the wall temperature owing to thermal equilibrium. 38,39 The detail of the calculations is described in Supporting Information. The exit aperture was positioned closely at the input of the wavy Stark velocity filter.…”