Collisional deactivation of N2O(001) studied by time-resolved infrared fluorescence

Abstract

The time-resolved infrared fluorescence ͑IRF͒ technique has been used to study the vibrational deactivation of excited N 2 O by large polyatomic colliders at ambient temperature ͑295Ϯ2 K͒. N 2 O͑00 0 1͒ molecules were prepared by direct pumping with the P͑18͒ line of a pulsed CO 2 laser at 9.536 m. The bimolecular rate constant for self-deactivation was determined to be ͑0.763Ϯ0.006͒ϫ10 3 Torr Ϫ1 s Ϫ1 , in very good agreement with previous work. The rate constants for deactivation by Ar and H 2 were found to be ͑0.103Ϯ0.003͒ and ͑4.89Ϯ0.52͒ϫ10 3 Torr Ϫ1 s Ϫ1 , respectively. The deactivation rate constants for the large polyatomic molecules, c-C

Principal Energy Transfer Pathways in the Collision of N2O(0001) with Toluene-d8. A (WKB) Semiclassical Study

“…At 295 °C the calculated probability is 0.033, representing a fairly efficient energy transfer process. This value compares well with the observed probability of 0.023 . The temperature dependence of calculated probabilities over the temperature range 100−500 K is shown in Figure .…”

“…The lower two curves are for N 2 O(00 0 1) + C 6 D 5 CD 3 (ν 7 =0) → N 2 O(00 0 0) + C 6 D 5 CD 3 (ν 7 =1) + Δ E = −36 cm -1 and N 2 O(00 0 1) + C 6 D 5 CD 3 (ν 20 =0) → N 2 O(00 0 0) + C 6 D 5 CD 3 (ν 20 =1) + Δ E = −38 cm -1 based on the short-range interaction model of ref . The experimental point (□) is taken from ref . …”

“…Gas-phase energy transfer in molecular collisions has been the subject of continuing interest in chemistry and physics for the past several decades. − In recent years, collisions involving large organic molecules have been studied extensively, revealing valuable information on the rates and the mechanisms of deactivation of the excited molecules through vibration−translation (VT) and/or vibration−vibration (VV) processes. Such collision processes as well as collision-induced intramolecular VV energy transfer are attractive systems for study, since a larger molecule can provide a number of near-resonant energy transfer pathways. − The importance of such a near-resonant condition has recently been examined by Poel, Alwahabi, and King in their study of energy transfer from N 2 O(00 0 1; 2224 cm -1 ) to large organic molecules. − Since the CD stretching frequencies of many deuterated hydrocarbons are 2224 ± 100 cm -1 , N 2 O(00 0 1) is a particularly useful reagent in preparing large organic molecules in an excited state.…”

Collisional Deactivation of CO2(0001) and N2O(0001) by Toluene Isotopomers: Near-Resonant Energy Transfer from N2O(0001)

“…The IRF decay curves are similar to those obtained previously for CO 2 (00 0 1) and N 2 O(00 0 1) with other collider gases. 26,27 Typical IRF decay curves are shown in Figure 2 of ref 26 for CO 2 (00 0 1) and in Figure 1 The slope of the k obs versus pressure plot yields the bimolecular deactivation rate constant, k A-M , where A is CO 2 or N 2 O and M represents the collider gas. The k A-M are summarized in Table 1.…”

“…The deactivation rate constants have been scaled to the Lennard-Jones collision rate constant, k LJ , to yield the deactivation probabilities, P LJ , shown in Table 1. The values shown for the k LJ were taken, where appropriate, from our previous work 26,27 or were calculated using the method and data sources described previously. 26,27…”