Rates of collision-induced electronic relaxation of single rotational levels of SO2 (<i>A</i>̃ 1<i>A</i>2): Quenching mechanism by collision complex formation

We present measurements of collisional fluorescence quenching cross sections of NO(A(2)Σ(+), v' = 0) by NO(X(2)Π) and O2 between 34 and 109 K using a pulsed converging-diverging nozzle gas expansion, extending the temperature range of previous measurements. The thermally averaged fluorescence quenching cross sections for both species show a monotonic increase as temperature decreases in this temperature range, consistent with earlier observations. These new measurements, however, allow discrimination between predictions obtained by extrapolating fits of previous data using different functional forms that show discrepancies exceeding 120% for NO and 160% for O2 at 34 K. The measured self-quenching cross section is 52.9 Å(2) near 112 K and increases to 64.1 Å(2) at 35 K, whereas the O2 fluorescence quenching cross section is 42.9 Å(2) at 109 K and increases to 58.3 Å(2) at 34 K. Global fits of the quenching cross section temperature dependence show that, when including our current measurements, the low temperature behavior of the quenching cross sections for NO and O2 is better described by a parameterization that accounts for the long-range interactions leading to the collisional deactivation via an inverse power law model.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Low-temperature collisional quenching of NO A2Σ+(v′ = 0) by NO(X2Π) and O2 between 34 and 109 K

Sánchez‐González

Eveland

West

et al. 2014

“…The interaction potential has been described 19 by the multipole forces model. 32,33 However, the authors were not able to reproduce the significant dependence of the quenching rate constants on the rotational level N by their calculation. As has been discussed previously in detail, this classical model has its shortcomings 33 and quantum chemical calculations would be more successful.…”

Section: Quenching Of Ch"avä0n…mentioning

confidence: 98%

Rotationally resolved quenching and relaxation of CH(A2Δ,v=0,N) in the presence of CO

Meden

Kind

Stuhl

2002

Rate coefficients for reaction and for rotational energy transfer in collisions between CN in selected rotational levels ( X Σ + 2 , v = 2 , N = 0 , 1, 6, 10, 15, and 20) and C 2 H 2 Fate of isolated CH (B 2 Σ − ,v=0,J) states in inelastic collisions with CO Kinetic properties of the single rotational states 2рNр8 of the electronically excited CH(A 2 ⌬,vϭ0) radical have been studied in the gas phase at room temperature in the presence of CO. Rate constants of the state-to-state relaxation are presented. Further, rate constants were determined for the electronic quenching of single N states and compared with data recently reported by Cerezo and Martin ͓J. Photochem. Photobiol., A 134, 127 ͑2000͔͒. The radiative lifetimes of the rotational levels are given, too.

“…The lack of correspondence in this approach between the correlation of Q with collider and the temperature dependence of Q has been noticed before. 25,30 Beginning with a concept of Lee and co-workers, 31 Fairchild et al 25 developed a simple collision complex capture trajectory calculation on a one-dimensional attractive curve. The curve is built up from dipole-dipole, dipolequadrupole, quadrupole-quadrupole, dipole-induced-dipole, and dispersion forces plus a centrifugal barrier that varies with collision energy.…”

Section: Descriptions In Terms Of Attractive Forcesmentioning

confidence: 99%

Vibrational energy transfer in OH A 2Σ+ between 195 and 295 K

Steffens

Crosley

2000

Fate of isolated CH (B 2 Σ − ,v=0,J) states in inelastic collisions with COVibrational energy transfer ͑VET͒ vЈϭ1→0 and electronic quenching of vЈϭ1 and 0 in the A 2 ⌺ ϩ electronically excited state of the OH radical has been studied over the temperature range 195 to 295 K. The colliders investigated were N 2 , O 2 , and CO 2 . Laser-induced fluorescence experiments were conducted in a flow cell with photolytic production of OH; both fluorescence intensity and time decay measurements were made. The VET cross sections are found to increase with decreasing temperature, suggestive of attractive force interactions in the VET process.