Atom transition, optical

In equations (Cl. 4.4) and (Cl. 4.5) Acoj = cu - coj is the detuning of the optical field from the atomic transition frequency Q is the natural width of the atomic transition and m is tenned the Rabi frequency and reflects the... 

Figure lb shows a four-level system. The terminal level, level 2, is ordinarily empty. Atoms are optically pumped to level 4. From level 4, the atoms make a rapid radiationless transition to level 3. The first few atoms to arrive begin to contribute to the population inversion. Therefore, laser operation can begin with much less intense pumping light. After the laser transition, the atoms return to the ground state (level 1) by a radiationless transition. 

Fig. 6. Optical spectrum of Ir atoms isolated in solid Ar at 10-12 K, compared to the gas-phase atomic transitions of Ir. The stick heights correspond to reported oscillator strengths of gaseous Ir atoms (49).

Techniques other than UV-visible spectroscopy have been used in matrix-isolation studies of Ag see, for example, some early ESR studies by Kasai and McLeod 56). The fluorescence spectra of Ag atoms isolated in noble-gas matrices have been recorded (76,147), and found to show large Stokes shifts when optically excited via a Si j — atomic transition which is threefold split in the matrix by spin-orbit and vibronic interactions. The large Stokes shifts may be explained in terms of an excited state silver atom-matrix cage complex in this... 

If an atomic transition is optically pumped by a beam of laser radiation having the appropriate frequency, the population in the upper state can be considerably enhanced along the path of the beam. This causes an intensification of the spontaneous emission from this state, which contains information about the conditions within the pumped region, since the exponential decay time for the intensified emission depends upon both the electron number density and the electron temperature. The latter can be obtained from the intensity ratio of the fluorescence excited from two different lower levels, if local thermal equilibrium is assumed. This method has been dis-... 

Chiral Metal Atoms in Optically Active Organo-Transition-Metal Compounds, 18, 151 13C NMR Chemical Shifts and Coupling Constants of Organometallic Compounds, 12, 135 Compounds Derived from Alkynes and Carbonyl Complexes of Cobalt, 12, 323 Conjugate Addition of Grignard Reagents to Aromatic Systems, I, 221 Coordination of Unsaturated Molecules to Transition Metals, 14, 33 Cyclobutadiene Metal Complexes, 4, 95 Cyclopentadienyl Metal Compounds, 2, 365... 

M.J. Seaton, Strong coupling in optically allowed atomic transitions produced by electron impact, Proc. Phys. Soc. (London) 77 (1961) 174. 

Chiral Metal Atoms in Optically Active Organo-Transition-Metal... 

This article is confined to organo-transition-metal compounds having chiral metal atoms whose optical activity has been demonstrated. Only those compounds are discussed in detail for which there is a choice with respect to the metal configuration and for which a separation or at least an enrichment of isomers with opposite metal configuration has been achieved. After the treatment of such topics as optical resolution, optical purity, optical stability, optical induction, stereochemistry of reactions, relative and absolute configurations, Table I (Section XVII) collects the information available for the compounds under consideration. 

SCOPE OF THE CONCEPT OF CHIRAL METAL ATOMS IN OPTICALLY ACTIVE ORGANO-TRANSITION-METAL COMPOUNDS... 

The fluorescence technique, like other methods based on scatter (elastic or inelastic), has been shown by us - and others to be a reliable unperturbing method of measuring spatial/ temporal flame temperatures and species concentrations. To avoid the dependency of the fluorescence signal on the environment of the emitting species, it has been shown by several workers that optical saturation of the fluorescence process (i.e., the condition occurring when the photoinduced rates of absorption and emission dominate over the spontaneous emission and colli sional quenching rates) is necessary. Pulsed dye lasers have sufficient spectral irradiances to saturate many transitions. Our work has so far been concerned with atomic transitions of probes (such as In, Pb, or T1) asoirated into combustion flames and plasmas. 

At the same time very often the real optical field interacting with atoms ha.s rather broad spectral profile, width of which is broader or comparable with the inhomogeneous width of the atomic transition. In this case, a broad spectral line approximation for quantum density matrix approach has proved to be verj- rewai d-ing. This approximation was introduced in the 1960s by C. Cohcn-Taimoudji for excitation of atoms with ordinai-y light sources [10]. This was an era before lasers. Later on it was adjusted for application for exedtation of atoms wdth multimode lasers [11] and for excitation of molecules in the case of large angular momentum states [3, 12]. 

Thus far, studies of coherent optical processes in a PBG have assumed fixed (static) values of the atomic transition frequency [Quang 1997], However, in order to operate quantum logic gates, based on pairwise entanglement of atoms by field-induced dipole-dipole interactions [Brennen 1999 Petrosyan 2002 Opatrny 2003], one should be able to switch the interaction on- and off-, most conveniently by AC Stark-shifts of the transition frequency of one atom relative to the other, thereby changing its detuning from the PBG edge. 

The interest in quantum interference stems from the early 1970s when Agarwal [4] showed that the ordinary spontaneous decay of an excited degenerate V-type three-level atom can be modified due to interference between the two atomic transitions. The analysis of quantum interference has since been extended to other configurations of three- and multilevel atoms and many interesting effects have been predicted, which can be used to control optical properties of quantum systems, such as high-contrast resonances [5,6], electro-magnetically induced transparency [7], amplification without population inversion [8], and enhancement of the index of refraction without absorption [9]. 

The simplest quantum source of photons is the atomic transition, creating, according to the selection mles, multipole photons. The simplest model of the interaction of an atom with the electromagnetic radiation is associated with the notion of so-called two-level atom [64]. In fact, this model originates from the famous study of radiation kinetics by Einstein [65]. With the development of laser, the notion of two-level atom entered firmly into the practice of quantum optics. The fact is that, using lasers as sources of electromagnetic radiation, one... 

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