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The two‐photon, laser‐assisted reaction between Xe and Cl2 has been used to generate XeCl(B,C) molecules for subsequent kinetic studies at 300 K. Two‐body quenching rate constants for the collisionally coupled XeCl(B,C) molecules were determined from the pressure dependence of their decay rates on added molecular gases. The quenching constants for XeCl(B,C) by most molecules are large, even though acceptor electronic states are not available for quenching by an excitation‐transfer mechanism. At higher pressure (>100 Torr) of Xe, Xe2Cl(4 2Γ) molecules were formed via three‐body quenching of XeCl(B,C), and the quenching rate constants for Xe2Cl(4 2Γ) by added gases were determined and compared with those for XeCl(B,C). In all cases, the quenching rate constants for XeCl(B,C) are larger. The two‐body quenching mechanisms for XeCl(B,C) and Xe2Cl(4 2Γ), which are ionic molecules, are discussed. Three‐body quenching of XeCl(B,C) with formation of Xe2Cl(4 2Γ) was observed for Xe+N2, Xe+CF4, and Xe+SF6.

The two‐photon, laser‐assisted reaction between Xe and Cl2 has been used to prepare XeCl (B,C) molecules in Xe and in Xe mixtures with lighter rare gases for kinetic studies of the coupled XeCl (B,C) states. The XeCl (B–X) spectra were used to assign the conditions for which the vibrational temperature was nearly 300 K. Relative intensity and coupled radiative lifetime measurements provide independent data which support an energy separation between the XeCl(B) and XeCl(C) states of ∼100 cm−1. The two‐body quenching rate constant in Xe for XeCl (B,C) was measured as 5+3−2×10−12 cm3 s−1, and a three‐body quenching rate constant of 13±4×10−31 cm6 s−1 is indicated. Experiments also were done with added Kr, Ar, Ne, and He to establish two‐body and mixed (e.g., Xe+Ar) three‐body quenching rate constants. The three‐body quenching rate constants are nearly equal to the Xe2Cl* formation rate constants and three‐body dark quenching of XeCl(B,C) is negligible.

Sensitized reactions of Xe and Kr with halogen donors in the presence of high buffer gas pressures of Kr and Ar, respectively, have led to the observation of five emission bands in the ultraviolet region of the spectrum. These broad structureless bands are assigned to the mixed rare gas–halide trimers KrXeCl, KrXeBr, KrXeI, ArKrF, and ArKrCl. Despite an extensive search, no emission corresponding to KrXeF could be found and this mixed trimer may be unstable because of interaction with a lower repulsive state. The positions and half‐widths of the five emission bands are characterized, and the formation mechanism of the mixed trimers in these experiments is discussed.

The rate constants for XeF(B,C), XeCl(B,C), and XeI(B,C) formation from reactions of Xe(3P1) and Xe(3P2) with NF3, N2F4, NF2, CCl4, and CF3I have been measured relative to XeCl(B,C) formation from the reactions with Cl2. The XeCl(B,C) formation rate constants from Cl2 are assumed to equal the total Xe(3P2) and Xe(3P1) quenching rate constants. The dependence of the XeX* formation rate constants upon reagent for Xe(3P1) and Xe(3P2) are similar with the polyatomic reagents having considerably smaller XeX* product formation rate constants than does Cl2. The previous claim from this laboratory that the XeF(B,C) formation rate constant from NF3 was approximately equal to the total quenching rate constant is revised downward in this work.