No abstract

An Yb 31 -doped optical fiber is laser cooled in vacuo from 298 to 282 K. Cooling results from anti-Stokes fluorescence of the ytterbium ions after optical pumping at a wavelength of 1015 nm. The sample temperature is deduced from the emission spectrum, which is sensitive to the populations in the excited-state multiplet of the ions. The temperature change is limited by the coupling between the fiber and ambient blackbody radiation, as confirmed when samples suddenly exposed to the pump laser are found to exponentially relax towards thermal steady state with the expected time constants. [S0031-9007(97)02372-7]

Laser-induced cooling of a solid by net anti-Stokes fluorescence, first experimentally demonstrated in 1995, can be the basis of a new type of cryocooler, an optical refrigerator. This article describes the physics and design issues of a practical optical refrigerator for operation at 77 K. In particular, the Los Alamos Solid-State Optical Refrigerator (LASSOR) which we are developing would have an operating efficiency comparable to commercial small cryocoolers, be completely vibration-free and operate for years without maintenance.

No abstract

Vibrational relaxation of N2 and CO2(001) by alkali metal atomsThe laser fluorescence technique coupled with ESR detection of atoms has been used to measure the vibrational relaxation of CO,(OO I) by 0(' P), Cl(' P), and F(' P). The rates are k cO,-o = 6.69 X 10 3 (sec-Torr)-l, kCO,.Cl = 4.91 X 105 (sec-Torr)-l and kCO,F = 1.04 X 105 (sec-Torr)-l These rates are much faster than those of rare gas atoms of similar atomic weights. Measurements were also made establishing limits for the relaxation of CO, by H('S), D(,S), and N(4S).