Energy levels and transitions

Figure Bl.13.1. Energy levels and transition probabilities for anIS spin system. (Reproduced by pennission of Academic Press from Kowalewski J 1990 Annu. Rep. NMR Spectrosc. 22 308-414.)...

Figure 1 Jablonski diagram showing energy levels and transitions F, fluorescence C, chemiluminescence P, phosphorescence CD, collisional deactivation IC, internal conversion ISC, intersystem crossing S0, ground singlet state S1( S2, excited singlet states Tl5 excited triplet state.

The y-energies are characteristic of the nuclear energy levels and transitions. Figure 10.12 shows the appearance of a y-ray spectrum. Such spectra are of immense value in the identification and determination of radionuclides in a radioactive mixture. 

Figure 9.23 Schematic arrangement of energy levels and transitions in a four-level laser. Internal transitions are marked with dotted lines.

Figure 1.19 Energy levels and transitions in the rhodamine 6G dye laser...

Figure 1.9 The energy-level and transition schemes and possible luminescence spectra of a three-level ideal phosphor (a) the absorption spectrum (b, c) emission spectra under excitation with light of photon energies hvi and /iV2, respectively (d, e) Excitation spectra monitoring emission energies at /i( V2 — vi) and at /i vi, respectively. Arrows mark the absorption/emission transitions involved in each spectrum. Eixed indicates that the excitation or emission monochromator is fixed at the energy (wavelength) corresponding to this transition.

Laser-induced fluorescence (LIF). Laser-induced fluorescence measurements have been applied to the atmosphere since the suggestion of Baardsen and Ter-hune in 1972 that this method should be feasible. Figure 11.43 shows the energy levels and transitions involved in LIF measurements. OH is excited from its ground X2n state into the first electronically excited A22 state. The v" = 0 to r = 0 transition is around 308 nm and the v" = 0 to v = 1 at 282 nm. Two schemes have been used excitation using 282 nm into v = 1 of the upper electronic state, or excitation using 308 nm into v = 0 of the upper state. Collisional quenching deactivates some of the v = 1 into u = 0 in competition with fluorescence, mainly in the (1,1) band of the electronic transition (that is, from v = 1 of the upper state into v" =1 of the lower state). Collisional deactivation of v = 0 then occurs in competition with fluorescence in the (0,0) band at 308 nm... 

Fig. 14. Schematic representation of energy levels and transitions for fluorescence and related processes kic, rate constant for interval conversion fcF, rate constant for fluorescence fcISC, rate constant for intersystems crossing fc[cp> rate constant for internal conversion from triplet state kp, rate constant for phosphorescence S, energy level for the first excited singlet state after solvent rearrangement for a polarity probe in a polar solvent.

Early investigators of the spectrum of helium believed that there were two kinds of helium, which they called orthohelium and parahelium each kind had its own set of energy levels, and transitions between the two kinds of levels did not occur. Explain these observations. 

Table A-2. Energy Levels and Transition Probabilities of Some Atoms of Photochemical Interest...

Energy Levels and Transition Probabilities of Some Atom of Photochemical Interest, 363 Conversion Factors for Absorption Cofficients, 373 Conversion Factors for Second Order Rate Constants, 37 1 Conversion Factors for Third Order Rate Constants, 374 Conversion from Pressure to Concentration Units, 375 Enthalpies of Formation of Atoms at 1 atm and 0°K in 11 . Idea Gas State, 375... 

Ar atom, energy levels and transition probabilities, 36 3T 5P, 1 P, sensitized reactions, 148 Ar+ laser, 116-117... 

As atom, energy levels and transition proli abilities, 369T J Dj,2 Pj, 160 AsCI, 160... 

Zr has a full lf7/2, lf5/2 2P3/2 and 2Pl/2 Photon shell and a full 199/2 neutron shell. Low-lying excitations with positive parity are due to proton excitations from the fp shell to the gg/2 orbital. In the model space lPl/2-299/2+21 excitations are restricted to J 8, and earlier calculations [GL074] account for energy levels and transition rates within these restrictions. We have chosen to expand the model space in following ways ... 

As stated earlier, the decoupled representation used above is most appropriate for the high field measurements of the magnetic resonance spectrum. Before examining the field dependence of the energy levels and transition probabilities, we recalculate the matrix elements of Xusing the coupled basis, J, I, F, MF). We note that for J = 1 and / = 1, we can have F = 2 (with Mp = 2, 1, 0), F = 1 (with Mp = 1, 0), and F = 0 (Mf = 0). 

The energy levels and transition frequencies can be obtained by diagonalising the above matrices, given suitable values of the molecular constants. The most accurate values were obtained by Muenter and Klemperer [87], and are as follows ... 

Before deriving quantitative expressions for general spin systems, we shall examine qualitatively the energy levels and transitions arising from two spin /2 nuclei that are not coupled or are only weakly coupled (AX system). As usual, we take the static imposed magnetic field to lie along the z axis, and we express the orientation of the ar component of nuclear spin /, as a or fi for Iz = x/2 or —V2, respectively. A system of N nuclei of spin x/2 is described by the 2N possible... 

Energy levels and transition frequencies involved in Raman spectroscopy. 

Figure I. Energy levels and transitions (schematic) for (left labels) and d complexes (right labels). The state symbols appropriate to pseudo-octahedral symmetry (O) are indicated.

Figure A3-8 illustrates the energy levels and transitions. Subtraction of the energies leads to four transition frequencies. By convention, the center of the spectrum is given zero frequency, so that (ua + ) =0. Consequently, the four transition frequencies are...

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