Transition probabilities hydrogen

W.L. Wiese, M.W. Smith, B.M. Glennon Atomic Transition Probabilities -Hydrogen through Neon (U.S. Government Printing Office, Washington... 

Jaquet and Miller [1985] have studied the transfer of hydrogen atom between neighbouring equilibrium positions on the (100) face of W by using a model two-dimensional chemosorption PES [McGreery and Wolken 1975]. In that calculation, performed for fairly high temperatures (T> rj the flux-flux formalism along with the vibrationally adiabatic approximation (section 3.6) were used. It has been noted that the increase of the coupling to the lattice vibrations and decrease of the frequency of the latter increase the transition probability. 

H. N. Russell analyzes solar spectrum with theoretical transition probabilities and eye estimates of line intensities. Notes predominance of hydrogen (also deduced independently by Bengt Stromgren from stellar structure considerations) and otherwise similarity to meteorites rather than Earth s crust. M. Minnaert et al. introduce quantitative measurements of equivalent width, interpreted by the curve of growth developed by M. Minnaert, D. H. Menzel and A. Unsold. 

Symmetry-forbidden transitions. A transition can be forbidden for symmetry reasons. Detailed considerations of symmetry using group theory, and its consequences on transition probabilities, are beyond the scope of this book. It is important to note that a symmetry-forbidden transition can nevertheless be observed because the molecular vibrations cause some departure from perfect symmetry (vibronic coupling). The molar absorption coefficients of these transitions are very small and the corresponding absorption bands exhibit well-defined vibronic bands. This is the case with most n —> n transitions in solvents that cannot form hydrogen bonds (e 100-1000 L mol-1 cm-1). 

A simple empirical relation which correlates most of the available experimental relaxation times available at temperatures in the neighbourhood of 300 °K is the Lambert-Salter plot30, which is shown in Fig. 10. Molecules fall into two classes, differentiated by the presence or absence of hydrogen atoms, each class showing a linear relation between log Zu 0 and vmIn. It is difficult to see any clear theoretical explanation of this striking correlation between vibrational frequency and transition probability which neglects entirely the influence of both mass and inter-... 

Another significant change is in the intensities of IR active vibrations t of the encapsulated CH4 molecule.These vibrations for CH4 Cs4 are an order of magnitude weaker than for CH4 C6oH36 due to the contributions of the outer C-H bonds in the latter to the spectral transition probabilities. Therefore, an IR study of the host-guest interaction in hydrogenated endofullerenes should be more informative than in clusters with bare carbon cages. 

We now have the opportunity to perform a laser resonance experiment to measure the Lamb shift in muonic hydrogen. Taking into account the muon stop rate, entrance detector efficiency, long-lived metastable 2S population, laser transition probability, solid angles and detection efficiency of the X-ray detector we estimate our event rate on resonance to be 9 events per hour. 

The radiation of a vibrational band is directly correlated to the vibrational population in the excited state I(v — v") = n(v ) x Av>v . Av>v is the transition probability. Thus, several vibrational bands which originate from different vibrational levels yield the corresponding vibrational population. In case of hydrogen or deuterium molecules the population of the first four or five vibrational levels, respectively, is accessible. Higher vibrational levels are disturbed by pre-dissociation processes. For further analysis, it is very convenient to use the relative vibrational population n(v )/n(v = 0). 

Two papers have attempted to compare the observed infrared lines of the base pairs in the region of the hydrogen-bond absorption with the calculated data. Rein and Svetina have calculated the proton vibrational states and relative transition probabilities for two guanine-cytosine hydrogen bonds. Their preliminary results seemed to be consistent with the absorption peak at 3489 cm (0.436 eV) reported by Pitha et for the hydrogen bond N-H stretching mode of... 

G.A.Kapralova, E.E.Nikitin, and A.M.Chaikin, Nonempirical calculations of the probabilities of vibrational transitions in hydrogen halide molecules, Chem. Phys. Lett. 2, 581 (1968)... 

Table 3 Energy shifts of K- and L-shell electrons in hydrogen-like due to various collective excitations. Upper half The contributions fixim low-lying nuclear states are calculated using experimental energies and transition probabilities [69]. Lower half The contributions from giant resonance states. Excitation energies and corresponding reduced electric transition strengths are again estimated based on empirical formulae. Notations are the same as in Table 2.

The selection rules of the new quantum theory allow electric dipole transitions between levels of the same n, but since the probability of spontaneous transition depends on the cube of the frequency, such transitions in hydrogen are exceedingly improbable. Stimulated transitions, on the other hand, may take place under quite small alternating electric fields of the appropriate frequency. Absorption and emission of energy by the atom are equally probable, so that a change in an assembly of atoms may only be detected if the two states between which transitions are taking place are unequally populated at the outset. 

---