Photofragment spectroscopy states

Methane-to-methanol conversion by gas-phase transition metal oxide cations has been extensively studied by experiment and theory see reviews by Schroder, Schwarz, and co-workers [18, 23, 134, 135] and by Metz [25, 136]. We have used photofragment spectroscopy to study the electronic spectroscopy of FeO" " [47, 137], NiO [25], and PtO [68], as well as the electronic and vibrational spectroscopy of intermediates of the FeO - - CH4 reaction. [45, 136] We have also used photoionization of FeO to characterize low lying, low spin electronic states of FeO [39]. Our results on the iron-containing molecules are presented in this section. 

Figure 10 The left-hand panel shows the excitation scheme used in a typical doubleresonance overtone photofragment spectroscopy experiment. The particular scheme shown here is used to prepare HOCl molecules with six quanta of OH stretching and many quanta of rotation, just above the dissociation threshold. The right-hand panel depicts sample double-resonance spectra of the HOCl(6ui <— 2vi) band. Each spectrum in the plot originates from a selected (J, K ) rotational state. Courtesy of T. R. Rizzo.

Photofragment spectroscopy of 03 between 457.9—752.5 nm has determined energy partitioning in the and O2 photofragments formed from ground and vibrationally excited (in the v, symmetric stretching mode) parent molecules. Predissociation of the h Lg and / rig states of has been studied. 

Laser-induced fluorescence photofragment spectroscopy studies with state-selective interfragment recoil measurement have not been performed to any appreciable extent. A preliminary kind of experiment has recently been carried out in an MPD case by using the time-of-flight technique under bulk condition and with rather limited spectral resolution. A Doppler spectroscopy study has been carried out in a one-photon dissociation case where electronically excited fragments were produced under bulk condition, and linewidth measurement was made in emission interferomet-rically. A first experiment with tunable LIF detection has been made recently by McDonald et al., who dissociated HN3 at 266 nm and... 

Photofragment spectroscopy.—The analysis of the angular distribution and energies of fragments arising from photodissociation, using polarized light, permits evaluation of the states involved in the dissociation process and an approach towards the ideal experiment in which microscopic reaction rates can be measured, and there has been much increased interest in this phenomenon in the past year, both from an experimental and theoretical standpoint. Papers... 

Hyperfine Interaction Constants. In the doublet states X 11 and A A, where the unpaired electron occupies the 2n or the 5o MO, respectively, hyperfine Interaction occurs between the electron spin (S=1/2) and the nuclear spin of P (1=1/2) or (1=1/2). This results in a splitting of the rotational levels into four sublevels. Hf splitting of the rotational lines have been observed in the v=1<-2 band of the A A -X rir system applying high-resolutlon laser photofragment spectroscopy [12, 13]. The following Frosch-Foley hf interaction constants a, bp (=b + c/3), c, d (see [36, pp. 34/8]) for the ip and nuclei have been derived (constants In MHz three standard deviation in parentheses) [13] ... 

Figure 2.5 Schematics of the concepts for (a) ionization-loss stimulated Raman spectroscopy (ILSRS), where resonant two photon ionization of the molecular parent, follows the depletion of ground state reactant species as a result of SRS and (b) VMP, where preexcited molecules are dissociated and the ensuing H photofragments are probed by (2 -I-1) resonantly enhanced multiphoton ionization. Reproduced with permission from Ref. [86]. Copyright (2009) AIP Publishing LLC.

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