Rovibrational structure

We are on our way testing if similar approaches can be applied to other, larger molecules such as pyrrole, thus with the hope to find regular patterns, supported by pseudo quantum numbers, allowing to frame the whole rovibrational structure, and therefore the IVR. 

Single-component unknowns can be identified by simply comparing their spectra with reference spectra, of which many catalogues are available (95). Reference spectra are also available in digitized versions, and searches of databases (qv) can be made rapidly by computer. Even if no reference spectrum of the unknown is available, the group frequencies may provide enough information for an experienced spectroscopist to make a full identification. The rovibrational structure in gaseous samples further increases specificity, and also furnishes an estimate of the sample temperature that may be useful in... 

The experimental data used for CuD and CuD come from the rovibrational structure of electronic transitions in optical spectra [45], whereas those used for CuH [43] as well as for and [44] come from the rotational... 

To account for the broadening of the experimental spectrum (related not only to the finite lifetime of the electronic state, but also to the rovibrational structure, collisions, and other aspects of the interaction between light and matter), and in particular to investigate whether certain bands may be hidden in the experimental spectrum due to overlapping bands, simple Lorentzian line broadening is often added in the form... 

Let us demonstrate that the tendency to narrowing never manifests itself before the whole spectrum collapses, i.e. that the broadening of its central part is monotonic until Eq. (6.13) becomes valid. Let us consider quantity x j, denoting the orientational relaxation time at ( = 2. If rovibrational interaction is taken into account when calculating Kf(t) it is necessary to make the definition of xg/ given in Chapter 2 more precise. Collapse of the Q-branch rotational structure at T = I/ojqXj 1 shifts the centre of the whole spectrum to frequency cog. It must be eliminated by the definition... 

Fig. 12. Partitionings of hydrogen fragment translational energy distribution into three components. The solid line denotes the contribution from H2S — 8H(,4 "S+ ) + H which yields a resolved structure with a rovibrational state assignment on the top. The dotted line denotes the contribution of hydrogen from the SH(442 +) —> S(3P) + H reaction, which is a reflection of the solid curve but the structure is smeared out. The corresponding rotational quantum numbers of the parent molecule SI I (A 2>l 1 ) l =0 is marked on the bottom. The remaining part of the P(E) spectrum is represented by the square-like dashed curve.

Hydroxyl radical (OH) is a key reactive intermediate in combustion and atmospheric chemistry, and it also serves as a prototypic open-shell diatomic system for investigating photodissociation involving multiple potential energy curves and nonadiabatic interactions. Previous theoretical and experimental studies have focused on electronic structures and spectroscopy of OH, especially the A2T,+-X2n band system and the predissociation of rovibrational levels of the M2S+ state,84-93 while there was no experimental work on the photodissociation dynamics to characterize the atomic products. The M2S+ state [asymptotically correlating with the excited-state products 0(1 D) + H(2S)] crosses with three repulsive states [4>J, 2E-, and 4n, correlating with the ground-state fragments 0(3Pj) + H(2S)[ in... 

R. D. Levine To answer the question of Prof. Lorquet, let me say that the peaks in the ZEKE spectra correspond to the different energy states of the ion. From the beginning one was able to resolve vibrational states, and nowadays individual rotational states of polyatomics have also been resolved. The ZEKE spectrum is obtained by a (weak) electrical-field-induced ionization of a high Rydberg electron moving about the ion. The very structure of the spectrum appears to me to point to the appropriate zero-order description of the states before ionization as definite rovibrational states of the ionic core, each of which has its own Rydberg series. Such a zero-order description is inverse to the one we use at far lower energies where each electronic state has its own set of distinct rovibrational states, known as the Bom-Oppenheimer limit. 

In the second case, reading eq.(26), it is necessary that at least one of the Q-space states has the same parity as the operator p. Then, in (26) there may be a non-zero off-diagonal element connecting the ingoing to the outgoing channels. This state is called here a transition state (TS) and the coordinates of the stationary arrangement of external Coulomb sources a°TS (or otTS) is defined as a transition state structure (TSS). The TSS is a fundamental electronic property, while the quantum states of the TS include translational and rovibrational states with their characteristic density of states. 

Resonance and threshold structures in fixed-nuclei electron-scattering cross sections are replicated, with characteristic energy shifts, in rovibrational excitation... 

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