Photodissociation wavelengths

Figure 22. OH A"I X"H (0. 0) [Q2a(2) + 02 (3) + Qi, (7)] LIF signal versus HI photodissociation wavelength, (a) Bulk conditions peaks caused by a suspected Ij impurity are marked with asterisks, (b) COj-HI complexes the arbitrary units are unrelated to those in (a). The circles were obtained by scanning slowly through the bandhead region. 

Because multiple scattering, surface reflection, clouds, and aerosols have a significant effect on radiative intensities at photodissociative wavelengths and consequently on the composition of the middle atmosphere (see, e.g., Luther et al, 1978), simplified radiative transfer... 

Briefly, oxygen can be photodissociated by solar UV of wavelength less than 242 run ... 

Vibrationally mediated photodissociation (VMP) can be used to measure the vibrational spectra of small ions, such as V (OCO). Vibrationally mediated photodissociation is a double resonance technique in which a molecule first absorbs an IR photon. Vibrationally excited molecules are then selectively photodissociated following absorption of a second photon in the UV or visible [114—120]. With neutral molecules, VMP experiments are usually used to measure the spectroscopy of regions of the excited-state potential energy surface that are not Franck-Condon accessible from the ground state and to see how different vibrations affect the photodissociation dynamics. In order for VMP to work, there must be some wavelength at which vibrationally excited molecules have an electronic transition and photodissociate, while vibrationally unexcited molecules do not. In practice, this means that the ion has to have a... 

S.3.4.3. Photodissociation It is also possible to use light as the activation method. Laser sources are especially useful because of their high intensity and narrow wavelength bandwidth. Photodissociation can be used to determine bond dissociation energies in ions directly, similar to what is done with threshold CID, or, alternatively, can be used in conjunction with direct ionization. 

Photodissociation of the water molecule is a model system for both experimental and theoretical studies. Extensive experimental and theoretical studies have been performed on this system during the last few decades. Excitation in its longest wavelength ultraviolet absorption band around 150-200nm leads to the lowest excited singlet state Dissociation... 

H2O, D2O and HOD with D detection at the Lyman-a wavelength excitation. Based on theoretical analysis, this single rotational state product propensity is attributed to a dynamically constrained threshold effect in the HOD photodissociation process.41... 

Table 1. Vibrational populations of 02(1AS) from the photodissociation of ozone with light of wavelength A.

The total fraction of C>2(v > 26) generated from the photodissociation of ozone at a particular wavelength is given by... 

The bimodal velocity distribution of the 0(3Pj) fragments produced via the triplet channel in the UV photodissociation of ozone has also been observed by Syage41,43>46 and Stranges et al.AA at photolysis wavelengths of 226 and 193 nm, respectively. Both authors measured anisotropy parameters for the fast and slow product pathways separately. 

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