Photodissociation single photon

Photofragment spectroscopy is extremely sensitive, but it has the disadvantage that one is only sensitive to absorption that leads to photodissociation. For single-photon experiments, this means that one is restricted... 

Owing to the symmetry property of an optical dipole transition, the data analysis for a photodissociation study is greatly simplified. The center-of-mass differential cross-section for a single-photon, dissociative process can be expressed as38,39... 

Photodissociation of O3 using 335 -352 nm radiation leads to the formation of 02(b Sg ), and studies indicate that absorption of only a single photon is involved. ... 

In the following section, two types of photodissociation will be discussed single-photon dissociation and VUV multiphoton dissociation. The examples given are those with which we have worked and so is not a complete list of photodissociation reactions for which internal energies of photofragments have been determined. Several excellent reviews of a more general nature are available in the literature. ... 

NH3. The single photon dissociation of NH3 between 185 and 214 nm has been studied extensively and has been shown to result in predominantly NH2(X 5,)+H. DiStefano et al. have shown that photodissociation of NH3 using a hydrogen discharge lamp results in a weak visible emission which they have assigned as NH2( ... 

As shown in Figure 33a, the S intensity resulting from the 2 -t- 1 REMPI of S( P2) in the 193-nm photodissociation laser F range of (0.5-10) X 10 photons/cm is linear, indicating that the formation of S atoms from thiophene is the result of single photon dissociation events. The S intensity due to 2 -I- 1 REMPI of S( D) is very low. Figure 33b depicts... 

In addition, the single-photon IR photodissociation spectrum of the C2H5+ ion weakly complexed with a single Ar atom was consistent with the cation having the structure 54 in the gas phase. ... 

Figure 15.1 Potential energy diagram showing single photon excitation and photodissociation of a diatomic molecule on a purely repulsive potential surface (i.e. direct dissociation)...

In Chap. 3, wave packet propagation could be observed for nearly all of the alkali dimer and trimer systems considered, over a rather long time compared to the wave packet oscillation period. The wave packet dynamics - a fingerprint of the excited molecule - definitely characterize the excited bound electronic state of these molecules. However, with the results on K3 (excited with A 800 nm), another phenomenon, which often governs ultrafast molecular and cluster dynamics, comes into the discussion photodissociation induced by the absorption of single photons. This photoinduced dissociation permits detailed study of molecular dynamics such as breaking of bonds, internal energy transfer, and radiationless transitions. The availability of laser sources with pulses of a few tens of femtoseconds today opens a direct, i.e. real-time, view on this phenomenon. 

For two Bom-Oppenlieimer surfaces (the ground state and a single electronic excited state), the total photodissociation cross section for the system to absorb a photon of energy ai, given that it is initially at a state x) with energy can be shown, by simple application of second-order perturbation theory, to be [89]... 

The extremely wide range of possible dissociation energies necessitates the use of different kinds of light source to break molecular bonds. Van der Waals molecules can be fragmented with single infrared (IR) photons whereas the fission of a chemical bond requires either a single ultraviolet (UV) or many IR photons. The photofragmentation of van der Waals molecules has become a very active field in the last decade and deserves a book in itself (Beswick and Halberstadt 1993). It is a special case of UV photodissociation and can be described by the same theoretical means. In Chapter 12 we will briefly discuss some simple aspects of IR photodissociation in order to elucidate the similarities and the differences to UV photodissociation. 

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