2003
DOI: 10.1063/1.1543945
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Experimental and theoretical determination of rotational-translational state-to-state rate constants for N2:He collisions at low temperature (3<T<20 K)

Abstract: We present an experimental determination of state-to-state rotational-translational ͑RT͒ rate constants of N 2 :He collisions in the vibrational ground state as a function of temperature in the range 3ϽTϽ20 K. Raman spectroscopy in supersonic expansions of N 2 /He mixtures is used to determine the primary data that, together with the N 2 :N 2 state-to-state RT rates previously determined ͓Ramos et al., Phys. Rev. A 66, 022702 ͑2002͔͒, are needed to solve the master equation according to a procedure that does n… Show more

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Cited by 13 publications
(15 citation statements)
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“…where k R-T is the R-T rate constant of the C-state. It is expected that k R-T for the C-state is of the same order as the reported state-to-state R-T rate constants of the ground state N 2 (ν = 0) in He at room temperature (k R-T ∼ 10 −10 -10 −11 cm 3 s −1 [25]). Hence, the time between R-T collisions, τ R-T (=1/k R-T • n He ) τ r,C at atmospheric pressure, where n He is the He number density.…”
Section: Gas Temperature Measurementssupporting
confidence: 52%
“…where k R-T is the R-T rate constant of the C-state. It is expected that k R-T for the C-state is of the same order as the reported state-to-state R-T rate constants of the ground state N 2 (ν = 0) in He at room temperature (k R-T ∼ 10 −10 -10 −11 cm 3 s −1 [25]). Hence, the time between R-T collisions, τ R-T (=1/k R-T • n He ) τ r,C at atmospheric pressure, where n He is the He number density.…”
Section: Gas Temperature Measurementssupporting
confidence: 52%
“…We have reported an experimental method substantially improved with respect to our previous works, 19,20 which allows us to obtain inelastic collisional state-to-state rate coefficients and cross sections as a function of the temperature and collisional energy, respectively. The simplest molecular system pH 2 has been employed as a methodological test, reaching temperatures well below the triple point.…”
Section: Discussionmentioning
confidence: 99%
“…This breakdown of equilibrium, which is progressive along the expansion in the so called "zone of silence," provides a unique medium for the experimental study of inelastic collisions in cold gases. [1][2][3][4][5][6][7][8] Such studies are quantitative in nature and demand, however, an accurate characterization of the local flow variables, usually the number density n, the rotational populations P i associated with the quantum states i, the translational and rotational temperatures, T t and T r , respectively, and the flow velocity v. While n, P i , and T r can be measured today with very good accuracy by means of Raman spectroscopy with high space resolution [9][10][11][12][13][14][15] as well as by other methods, [16][17][18] translational temperatures cannot be measured routinely along the zone of silence, at least within the first 100 nozzle diameters of the jet. This is the region of interest for the study of collisions.…”
Section: Introductionmentioning
confidence: 99%
“…It is convenient for the present purpose to refer the NS-system (13) to molar form by means of the equivalence given in Eq. (2). Keeping this in mind, and using the equation of continuity, the equations of conservation of linear momentum, and total energy reduce to…”
mentioning
confidence: 99%