Optical pumping theory

Duclqy, M. (1973). Nonlinear effects in optical pumping of atoms by a high intensity multimode gas laser. General theory, Phys. Rev. A, 8, 1844-1859. 

Ducloy, M. (1976). Non-linear effects in optical pumping with lasers. I. General theory of the classical limit for levels of large angular momenta, J. Phys. B At. Mol. Phys., 9, 357-381. 

Ducloy, M., Nonlinear Effec ts in Optical Pumping of Atoms by a High-Intensity Multimode Gas Laser. Genaral Theory. Phys. Rev. A, 8 (4) p. 1844 - 1859, (1973). Auzinsli, M.P. and R.S. Ferber, Optical-Pumping of Diatomic Molecules in the Electronic Ground State — Classical and Quantum Approaches. Phvs. Rev. A, 43 (5) p. 2374 - 2386, (1991). 

This simple model therefore gives as an estimate for the relative strength of MChA in absorption, the product of the relative strengths of NCD and MCD, a result that seems in line with physical intuition for a cross-effect. A detailed molecular theory for MChA in molecular liquids and gases has been formulated by Barron and Vrbancich [14]. It requires complete knowledge of all molecular transition moments involved and therefore cannot be easily used to obtain quantitative predictions. Very recently, the first ah initio calculations of MChA in simple molecules have appeared [15], and a prediction of very strong MChA in optically pumped atomic systems [16] was made. 

Appelt S, Baranga AB, Erickson CJ, Romalis MV, Young AR, Happer W. Theory of spin-exchange optical pumping of 3He and Xe. Phys Rev A 1998 58 1412-1439. 

These reports were followed by demonstrations of optically pumped lasing in ZnO [147, 148]. Using an Xe laser, Johnston [147] reported SE at 275 K from ZnO platelets but was unable to explain the data by exdton-LO-phonon theories. Later on, Reynolds et al. [ 149] showed optically pumped lasing in as-grown ZnO platelets using an HeCd laser with very low pump power (4 Wcm ) at 2 K. Extremely well-formed lasing modes were observed from which a changeover from absorption to emission could be clearly detected. 

All numbers are absolute shielding, in ppm, in spherical samples (or corrected to a spherical sample), oo stands for infinite dilution in H2O or D2O. OP, optical pumping ABMR, atomic beam magnetic resonance theory, nonrelativistic calculation rel, estimate based on relativistic calculations for rare gas atoms by Kolbc/a/. ... 

The isotope Hg has only two ground state magnetic sub-levels and so has served as an important test case for the basic theory of optical pumping, developed in more detail... 

The first theoretical attempts in the field of time-resolved X-ray diffraction were entirely empirical. More precise theoretical work appeared only in the late 1990s and is due to Wilson et al. [13-16]. However, this theoretical work still remained preliminary. A really satisfactory approach must be statistical. In fact, macroscopic transport coefficients like diffusion constant or chemical rate constant break down at ultrashort time scales. Even the notion of a molecule becomes ambiguous at which interatomic distance can the atoms A and B of a molecule A-B be considered to be free Another element of consideration is that the electric field of the laser pump is strong, and that its interaction with matter is nonlinear. What is needed is thus a statistical theory reminiscent of those from time-resolved optical spectroscopy. A theory of this sort was elaborated by Bratos and co-workers and was published over the last few years [17-19]. 

Figure 1.3. Real-time femtosecond spectroscopy of molecules can be described in terms of optical transitions excited by ultrafast laser pulses between potential energy curves which indicate how different energy states of a molecule vary with interatomic distances. The example shown here is for the dissociation of iodine bromide (IBr). An initial pump laser excites a vertical transition from the potential curve of the lowest (ground) electronic state Vg to an excited state Vj. The fragmentation of IBr to form I + Br is described by quantum theory in terms of a wavepacket which either oscillates between the extremes of or crosses over onto the steeply repulsive potential V[ leading to dissociation, as indicated by the two arrows. These motions are monitored in the time domain by simultaneous absorption of two probe-pulse photons which, in this case, ionise the dissociating molecule.

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