Transition wavelength

The study of spectroscopy has provided all of the information required to make a positive identification of molecules in space. More interestingly, once the spectrum of a molecule or atom is understood accurately, the interaction of the molecule with its surroundings can be understood as well. Atoms and molecules, wherever they are, can report on their local conditions and be used as probes. We shall see many of these examples where knowledge of molecular properties provides insight into astrochemistry. For example, the understanding developed below will take us from the transition wavelength of Ha to the radius of Jupiter. 

Calculate the transition wavelengths of the first four terms and the convergence wavelength for the Balmer series and identify the red transition responsible for the colour of the Orion nebula. 

Red shift The shift of a transition wavelength to longer, redder wavelengths associated with the relative separating distance between the object and an observer. 

Metal Transition Wavelength (nm) Energy of Excited Atoms (kj mol 1)... 

Dichroic mirror (or so called chromatic beam-splitter) reflects wavelengths of light below the transition wavelength value and transmits wavelengths above this value. 

Fig. 19 Top One-photon absorption (solid line), two-photon excitation ( ), and relative acid-yield efficiency (o) spectra of p.2 plotted versus transition wavelength. Bottom Logarithmic plot of [ff ] against power of the excitation beam at 745nm/80fs pulses the best-fit line has a slope of 2.3, indicating an approximate quadratic increase of acid yield with excitation intensity. Reproduced from [214] with permission from AAAS...

Lanthanide (III) Emissive (initial) state configuration Final state configuration Transition wavelength/nm... 

MBPT significantly improves the electron transition wavelengths, line and oscillator strengths, transition probabilities as well as the lifetimes of excited levels. Therefore, it seems promising to generalize such an approach to cover the cases of more complex electronic configurations having several open shells, even with n > 2. 

The variation of the pressure against the confinement radius is shown in Figure 6. Figure 7 shows the behavior of the ls-2p transition wavelength against different values of the Debye shielding parameter X and the... 

Figure 7 Transition wavelength for the 2p state of a compressed hydrogen atom under different confinement radii and Debye shielding. The screening parameters (au) are indicated along the horizontal lines. Reprinted with permission from Claude Bertout, Editor-in-Chief, A A (Ref. [172]).

Figure 14 Comparison of the experimental and theoretical results using different models for the transition wavelengths for Is - 2p, 3p and 4p of Ar17+. The plasma electron density and temperatures are those of Ref. [104]. Reprinted with permission from [176] 2008, EDP Sciences...

Kar and Ho [196] have estimated the oscillator strengths for different transitions, dipole and quadrupole polarizabilities of He for a wide range of the Debye screening parameters using explicitly correlated wavefunctions. Results presented by Kar and Ho [196] are very accurate and may be of substantial use for comparison with those from laser plasma experiments. The behavior of several singly and doubly excited states of He under screened potential was also accurately estimated by Kar and Ho [197] using correlated basis functions. Variation of the transition wavelength as a... 

Figure 20 Transition wavelengths of the helium atom immersed in plasmas in terms of the screening parameter k (au). Reprinted with permission from [197] 2007, Elsevier...

Table 6 Comparison between experimental and theoretical results of relativistic (R) non relativistic (NR) transition wavelengths of C4+, Al11+ and Ar16+. The experimental data have been extracted from Figure 1 of Nantel et al. [99], Figure 1 of Riley et al. [92] and Figure 2 of Woolsey et al. [104] for C4+, Al11+ and Ar16+, respectively. The transition wavelengths have been calculated at the experimentally quoted temperatures and densities...

To determine the excitation energy of the lowest electronic level the contributions in the absorption spectrum from transitions to different vibrational modes of the excited state have to be separated. In the deconvolution of the absorption spectra Gaussian line shapes are assumed for the transitions to the different vibrational levels. The analysis leads to the transition wavelength A00 for the excitation from the ground state to the zero vibrational level of the excited state. 

As of 1994 the agreement between experiment and theory in the observed transition wavelengths was of the order of 1000 ppm. Then, a new theory of Korobov [7] came in. Fig. 4 shows comparison between experiment and theory. Although Korobov s non-relativistic theory showed a dramatical improvement over the earlier theories, it revealed a systematic discrepancy of the order of 50-100 ppm. This urged Korobov and Bakalov to take into account relativistic corrections [17]. The relativistic corrections are systematically about 50 ppm for the Av = 0 transitions and about 100 ppm for the Av = 2 transitions, accounting for the experimental results very well. 

CM2(r 3) as well as physical constants. The term CM is the molecular orbital mixing coefficient for the platinum 5d orbital, and the r"3 average is taken over the platinum d radial function. The differences in energy of the ground and first excited A2g and Eg states are given in terms of the transition wavelengths, A. 

Molecule Transition Wavelength A Other transitions Column densities Source Year of discovery... 

Element Transition Wavelength, X (in first order of reflection) Remarks... 

Fig. 7.12. The n = 4 energy level diagrams for Mo32+ (top) and Kr26+ (bottom) with the left ordinates expressed in the transition (to the ground state) wavelengths and the right ordinates in eV. Upper levels for s are on the left and d on the right. Measured transition wavelengths (to the ground state) are given for each of the...

Table 4 Transition wavelength, ground-state dipole, fj , transition dipole, p," and dipole differences, Ap , associated with low-lying CT bands for a series of ID NLO-phores (from EOAM). Second-order polarizabilities were estimated on the basis of (55). 

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