Argon excited diatomic molecules Ar*2(3𝒥+u)were produced by irradiating argon gas with short electron beam pulses. The kinetic behavior was studied by monitoring the time dependence of the 987.6 nm absorption band due to Ar*2 under various conditions.The method is largely different from the vacuum UV emission spectroscopy used previously in such kinetic studies. Ar*2 was found to be produced by a three-body reaction with a rate constant of (1.0±0.3) ×10−32 cm 6 sec−1. Then, the rate constants and cross sections of energy transfer were determined for 12 fundamental acceptor molecules. The theoretical formula proposed previously for Penning ionization was applied to energy transfer between Ar*2 cross sections given by the formula have the values comparable to the observed ones.

Articles you may be interested inThe spectroscopy and single vibronic level fluorescence quantum yields of jet cooled transstilbene and its van der Waals complexes J. Chem. Phys. 78, 5493 (1983); 10.1063/1.445477Spectroscopic studies on naphthalene in the vapor phase. II. Fluorescence quantum yields from single vibronic levels in the first excited singlet state-behavior of higher excited singlet statesThe quantum yields of fluorescence from the second excited singlet state of thiophosgene vapor have been measured as a function of pressure for eight S,<-So transitions, and parameters for the decay of the levels pumped have been calculated. The results indicate that reassignment of the origin of the S,<-So band system to 35112 from 36007 cm-1 is necessary. Quantum yields of fluorescence from the lowest levels in S, are extremely high (0.50 to 1.0) and are indicative of a very slow radiationless decay rate. Weakening of fluorescence from higher S, vibrational levels is most likely caused by predissociation.

The S2–S0 absorption, emission, and excitation spectra of thiophosgene vapor have been measured and the observed single vibronic transitions assigned. Comparison of the absorption and excitation spectra reveals that emission is excited only when transitions to the upper state terminate in 3m4n, m or n=0 or 1, and that the upper state is depopulated by rapid radiationless processes when higher vibrational levels are populated. The most prominent bands in the emission spectrum are those in which the transitions terminate in 1p3q4r with 1⩽p⩽10, 1⩽q⩽5, and 1⩽r⩽4. All three types of spectra are consistent with a pyramidal excited state in which the equilibrium internuclear distances are substantially greater than those of the ground state. The implications of this fluorescence ’’anomaly’’ with respect to the nature of radiationless processes in the thiophosgene are discussed.

Two types of transient absorptions due to excited diatomic molecules have been observed for neon, argon, and krypton irradiated with electron beam pulses in following wavelength regions: 8000 to 8200 Å and 9000 to 10 300 Å for neon, 9500 to 10 000 Å and 11 400 to 13 000 Å for argon, and 9500 to 10 000 Å and 11 600 to 14 000 Å for krypton. The first absorptions located at shorter wavelengths consist of several discrete bands and their lifetimes are longer than those of the second absorptions located at longer wavelengths. In addition, the intensities of the second absorptions are much weaker than those of the first absorptions. We have failed to observe the second absorption of xenon, which may be located at longer wavelengths than the observation limit. The time-dependent changes of absorption spectra suggest the formation of vibrationally and rotationally excited molecules. We attribute the lower state of the first absorption to the lowest triplet state 1u(3Σ+μ) and the upper one to the state 3Πg resulting from a combination of a ground state atom p0(1S0) and any of low-lying Paschen 2p excited atoms. The lower state of the second absorption is attributed tentatively to the lowest excited singlet state O+μ(1Σ+μ), while the upper state may be to 1Πg or 3Σ+gO.

Articles you may be interested inNonradiative decay of the lowest excited singlet state of 2-aminopyridine is considerably faster than the radiative decay