Gas phase molecular relaxation at very low temperatures. A comparative study of N 2 and its mixtures with He and Ne

• Published in: Vacuum Vol. 64; no. 3; pp. 417 - 423
• Main Authors: Aoiz, F.J., Bañares, L., Herrero, V.J., Martı́nez-Haya, B., Menéndez, M., Quintana, P., Tanarro, I., Verdasco, E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2002
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/S0042-207X(01)00298-6

The low temperature (<100
K) relaxation of N
2 in self-collisions and in collisions with He and Ne has been experimentally studied with resonance-enhanced-multiphoton-ionization and time-of-flight techniques. The following average values of the rotational relaxation cross sections,
σ
r, have been derived from the measurements:
σ
r
N
2–N
2
(
T=5–60
K)≈35
Å
2;
σ
r
N
2–He
(
T=5–80
K) ≈15
Å
2 and
σ
r
N
2–Ne
(
T=5–60
K)≈40
Å
2. The cross section trend
σ
r
N
2–N
2
≈
σ
r
N
2–Ne
>
σ
r
N
2–He
reported in the literature for
T=300
K is confirmed below 100
K, but the absolute values are larger in the low temperature range.