Single vibronic level fluorescence

If emission is from only one vibrational level of the upper electronic state it is referred to as single vibronic level fluorescence (or phosphorescence). 

Figure 9.33 Single vibronic level fluorescence spectra obtained by collision-lree emission Irom the zero-point level of the state of (a) pyrazine and (b) perdeuteropyrazine. (Reproduced, with permission, Ifom Udagawa, Y., Ito, M. and Suzuka, I., Chem. Phys., 46, 237, 1980)...

Figure 9.49 Single vibronic level fluorescence spectrum of styrene, in a supersonic jet, with excitation in the Ojj band...

Also worthy of comment is the survey of the single-vibronic-level fluorescence spectra of benzene published recently.13 The study confirms that the dominant fluorescence structure from every emitting level is that arising from transitions in which the e2g mode ve changes quantum number by 1, while = 0 for all other modes except vt. All other transitions are at least an order of magnitude... 

Continuous emission from NOa 359 and single vibronic level fluorescence from NOa 360 have been reported. The lifetimes of the 2Bl K > 0) states were measured, and the interesting result was obtained that the lifetime of the K = 4, N = 16 1 level was 36 [xs, substantially greater than that of the K = 0 levels. The increase in lifetime is attributed to Renner interaction of the and 2AX components of the linear 2 state. Rotational excitation has been shown to assist in the dissociation of NOa in the 249.1 nm system, but this is minor in extent compared with that observed in the 397.9 nm system. Yields of 0(4)) were reported.361 The photolysis of NOa has been further studied.362 In the report by Harteck et al., a two-photon excitation process was observed when a pulsed ruby laser was used for excitation. Thermal and photochemical reactions of NOa with butyraldehyde,363 other aldehyde-NO systems,364 and methylperoxyl radical-NOx reactions 365 have been discussed. 

SOM HaS Reactions.—The photolysis of SOa in Ha at 147 nm and 116—123.6 nm has been studied,388 and emission from OH(/f - X), S ( -> X), and SO(B -+ X) was observed in addition to SOa fluorescence. The quantum yield of S03 formation was found to be <0.4 at 123.6 nm. A fuller paper has appeared on single vibronic level fluorescence from the state of SOa vapour. This confirms that there are two different groups of rovibronic states, one of which is very long-lived (80—600 (is), the other being short ( 50 (jis) and with a bimolecular quenching rate-constant that is an order of magnitude greater than the gas-kinetic rate.388 The extensive implications of this important observation were discussed in Volume 5,887 and will not be repeated here. 

There are quite a few experimental data on tropolone. The electronically ground state X( Ai) has been studied by infrared (IR) spectroscopy [71,72], Fourier transform microwave spectroscopy [73], and single vibronic level fluorescence (SVLF) spectroscopy [74-76]. IR spectra give us information about normal modes. The SVLF spectra provide us with the relation between the vibronic level in the excited state and that in the ground state. For the first electronically excited state ACB2), the UV absorption spectra [77] and the laser fluorescence excitation spectra [70,74,76,78] have been measured. The latter have also been measured for the isotope substituted tropolone [79,80]. The data obtained from the laser fluorescence excitation spectra... 

Alves, A.C., Hollas, J.M., Musa, M., and Ridley, T. (1985) The 370-nm electronic spectrum of tropolone evidence from single vibronic level fluorescence spectra regarding the assignment of some vibrational fundamentals in the X and A states. J. Mol. Spectrosc., 109, 99. 

Parmenter, C.S. and Schuyler, M.W (1970) Single vibronic level fluorescence. III. Fluorescence yields from three vibronic levels in the Bj state of benzene. Chem. Phys. Lett., 6, 339. 

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