Pumping by Energy Transfer

CSg + O2 / hv First report of a chem. CO laser, spectroscopy, chemical pumping scheme Pollack 200) 

CSa + O2 /e Discharge initiation of the pumping sequence, spectra Arnold, Kimbell 201) 

CS3 + Og / e Pulse discharge initiated CO laser Jacobson, Kimbell 202) 

CS2 + O2 1 hv Chemistry and performance characteristics, computer simulation Suart, Dawson, Kimbell 126) 

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OFRR Lasers Pumped by Energy Transfer 19.4.1 FRET Laser Concept... 

There are several ways of creating the requirednon-equilibrium situation, chemical reactions being one way. Chemical lasers are thus defined as lasers where a population inversion is effected by selective chanelling of the energy of a chemical reaction into certain excited product states. We also include in this discussion lasers which are pumped by energy transfer from a chemically excited species to an admixture which is then capable of lasing, and lasers... 

Quite similar to this pumping scheme was an attempt to pump a CO2 laser by chemical means reported by Russian workers 67>. Vibrationally excited N2 was produced by flash-photolyzing hydrazoic acid (HN3) and subsequent energy transfer. However, pumping by energy transfer from hydrogen... 

Earlier than with pulsed chemical lasers, the first technological breakthrough in chemical lasers occurred for continuous-wave lasers. Almost simultaneously in 1968 two groups successfully operated continuous-wave chemical lasers. One was at the Aerospace Corporation headed by T. A. Jacobs 75>, the other one at Cornell University under T. A. Cool 76>. One of these lasers was an HF laser the other was that is now called a hybrid chemical laser, being pumped by energy transfer rather than by a direct chemical reaction. This laser principle has been described in the context of pulsed chemical lasers in Section 6.5, In addition to these devices, an HF cw laser having millisecond flow duration was also demonstrated in principle in a shock tunnel. The latter employed diffusion of HC1 into a supersonic stream containing F atoms 77>. 

The efficiency of solid-state lasers (that is the ratio of laser output power to pump power) can often be increased by energy transfer from other excited ions with which the crystal was doped additionally 0. In this way energy transfer processes can be studied... 

Fluorescence Sensitization. The optical pumping efficiency and thereby the prospects for oscillation of several actinides may be improved by codoping with sensitizer ions using schemes similar to those employed for the lanthanides in Table IV. For example, the first excited J states of l)3+, Np3+, and Pu3+ could be sensitized by energy transfer from lanthanide codopants such as Ho3+, Er3+, Tm3+, and Yb3+ as in the "alphabet" Ho3+ scheme (31). Other schemes using actinides include Cf3+-sensitized Bk3+ ( 4- 6), l)3+-sensitized Np3+... 

Davis M J 1995 Trees from spectra generation, analysis, and energy transfer information Molecular Dynamics and Spectroscopy by Stimulated Emission Pumping ed H-L Dai and R W Field (Singapore World Scientific)... 

The dynamics of fast processes such as electron and energy transfers and vibrational and electronic deexcitations can be probed by using short-pulsed lasers. The experimental developments that have made possible the direct probing of molecular dissociation steps and other ultrafast processes in real time (in the femtosecond time range) have, in a few cases, been extended to the study of surface phenomena. For instance, two-photon photoemission has been used to study the dynamics of electrons at interfaces [ ]. Vibrational relaxation times have also been measured for a number of modes such as the 0-Fl stretching m silica and the C-0 stretching in carbon monoxide adsorbed on transition metals [ ]. Pump-probe laser experiments such as these are difficult, but the field is still in its infancy, and much is expected in this direction m the near fiitiire. 

The power required for pumping will be given by the product of the volumetric flowrate and the pressure difference between the pump outlet and the discharge end of the pipeline. Taking note of the fluctuating nature of the flow, it is necessary to consider the energy transferred to the fluid over a small time interval and to integrate over the cycle to obtain the mean value of the power. 

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