Band spectra, rotational

The emission spectrum observed by high resolution spectroscopy for the A - X vibrational bands [4] has been very well reproduced theoretically for several low-lying vibrational quantum numbers and the spectrum for the A - A n vibrational bands has been theoretically derived for low vibrational quantum numbers to be subjected to further experimental analysis [8]. Related Franck-Condon factors for the latter and former transition bands [8] have also been derived and compared favourably with semi-empirical calculations [25] performed for the former transition bands. Pure rotational, vibrationm and rovibrational transitions appear to be the largest for the X ground state followed by those... 

FIGURE 5.8 Complex hyperfine patterns due to axes noncolinearity in a low-symmetry prosthetic group. The X-band spectrum is from 65Cu(II)-bicarbonate in human serum transferrin (a,b) experimental spectrum (c,e) simulation assuming axial symmetry (d, f) simulation assuming triclinic symmetry with the A-axes rotated with respect to the g-axes over 15° about the gz-axis and then 60° about the new y -axis. Traces b, e, and f are 5x blow-ups of traces a, c, d, respectively (Hagen 2006). (Reproduced by permisson of The Royal Society of Chemistry.)... 

Benzo[c]furan (4) exhibits a long-wave absorption band of medium intensity in the region of 340 nm. Lack of solvent dependence together with mirror relationship to the fluorescence spectrum signifies a tt-ti band a rotational analysis of the vapor phase spectrum led to an assignment as 82 <- Ap 1,3-Diaryl-substituted benzo[c]furans show a strong absorption band in the region of 415 nm in sterically hindered compounds, this... 

Example Rotational Temperatures from Measurements of the CN Spectrum. The CN band spectrum was taken in a carbon arc from 25740 to 25800 cm. 1 (0-0 band). The relative intensities at 25760, 25770, and 25780 cm.-1 were found to be 21, 13.5, and 8.5%, respectively. What is the rotational temperature Figure 8 shows that T = 4000°K. Similarly, the vibrational temperatures could be determined by comparing the intensities of whole bands or small portions of the bands. 

The next step beyond pictorial patterns is a simple algebraic representation, which is based on the observed regularity of the pattern rather than any physical model. One expects that the energy levels Evj sampled in a band spectrum should be well represented by a simple, rapidly convergent, polynomial function of the rotational and vibrational quantum numbers, J and v. The Dunham expansion (1932),... 

Vibrational bands with rotational fine structure occur in the short infra-red region of the spectrum. The variations in I itself become... 

The A 2A- X 211 Emission Spectrum. The first time, the A X emission spectrum was excited in a hollow-cathode discharge through helium that contained small amounts of hydrogen and phosphorus vapor. A system of three red-degraded bands at 422.8, 385.4, and 356.7 nm was Identified with the v = 0- 1, 0 0, and 1 0 bands. Their rotational and fine structures are those expected for a transition, where the upper state approaches... 

The rovibronic spectrum presented in Fig. 26 was recorded at the highest power, of 5 x 10, obtained to date with the VUV laser-driven sources described here. This represents a factor of 3 to 5 improvement over spectroscopic resolution obtained with grating instruments in this wavelength region. The 25-0 band of Fig. 26 is one of 12 vibronic bands originating from v = 0 or 1 levels of the ground state to levels v = 23 to 31 of the excited state. For each of the 24-0, 25-0, 26-0, 26-1, and 27-1 bands, three rotational branches were clearly resolved. Three branches were less conspicuous in other bands or unobservable because of blending of lines, but all bands could be analysed in terms of P, Q, and R branches. 

In the molecule, the energy of a given state is determined not only by the distribution of the electrons but also by the particular state of the atomic nuclei building up the molecule. In addition to the energy of electron transition, there are energies involved in changing the states of oscillation and of rotation. This explains why the spectrum of a molecule consists of very many more lines than that of an atom. A mere glance shows that this is so, if one compares an atomic spectrum with a molecular spectrum the former can properly be described as a line spectrum, the latter as a band spectrum. 

Figure 7.6 LIE excitation spectrum for the CuI(C, u = 0—X, z/" = 0) band, with rotational line resolution, originating from the molecular beam reaction Cu -E I2 Cul + I. Level population information can be extracted from the spectral intensities (bottom). Experimental data adapted from Fang and Parson, J. Chem. Phys., 1991, 95 6413, with permission of the American Institute of Physics...

Concerning the non-equilibrium of each band spectrum, it should be also remarked that the band spectra of molecular ions sometimes show their rotational temperatures different from those of neutral molecules. As for nitrogen ions, a number of papers reported that the first negative system (INS), originated from B 2I + state of N2 ion, shows higher rotational temperature than that from neutral molecules (e.g., Huang et al., 2008). 

Finally, the Silsoft lens was allowed to dry and the valence spectrum was examined during the process. This spectrum can also be seen in Fig. 9. The valence band spectrum of the warming and drying lenses changes with time. The —CH group at 17 eV can be seen to increase in intensity with drying time. Thus, the low-surface-tension feature of this polymer rotates to the surface to minimize the interfacial surface tension. The growth of the peak at 17 eV takes about 20 min after the polymer has been completely dried. 

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