The thermodynamic behavior of single molecule-photon cryocooler(SMPC)was described by the study of participating frequency of phonons in light transitions, heat-light converting efficiency and cooling efficiency. The times of heat distribution were taken as a time scale in the investigation of cooling efficiency. The cooling efficiency curve obtained from our theory has the same shape of experiment curves obtained by other researchers. The reason of a bending of cooling efficiency curve appearing in the cooling region was given. The greatest cooling efficiency of SMPC was investigated, and it is obtained that the best wavelength, which results in the greatest cooling efficiency,is located at the point of one fourth exciting band width from the red edge. As a main conclusion, crystal-line materials are the sole kind of promising materials for obtaining the greatest cooling efficiency.

The Mo-doped titania exhibits a visible broadband emission under a 978 nm laser diode excitation. The luminescence has been assigned to the transitions from the excited states 3T1, 3T2 to the ground state 1A1 of the ［MoO4］2- radical. In TiO2∶Mo system, the p ower dependence of the upconversion-luminescence intensity exceeds a quadratic dependence, and the time evolution of the upconversion luminescence after the onset of continuous wave excitation is characterized by a rise time of 63 ms. These properties show the typical fingerprints of a photon avalanche. No luminescence was observed from the sample when excited with a pulsed laser (1064 nm) from a Nd∶YAG or a pulsed Raman-shift laser (953.6nm) pumped by a second harmonic of the Nd∶YAG. Regardless of the energy mismatch between the pulsed laser and the continuous wave diode laser, another reason may be that the duration time of a single laser pulse (10 ns) is much shorter than the rise time of the photon avalanche. The fluorescence “transfer function” theory is used to study the luminescence dynamics, which provides a good description of the experimental data.

This paper reports the theoretical calculation of the ambipolar diffusion coefficient in TDFWM-IL. We have obtained the ambipolar diffuion coefficient Da= 0.3cm2/s for CdS:Cu and compared with measured results for PbS ultrafine particles.

In this paper, a new mechanism of anti-Stokes fluorescent cooling based on the energy transfer among the centers within the inhomogeneously broadened line is proposed. The dependence of relative cooling efficiency on excitation photon energy and temperature is discussed.

Monte-Carlo simulation is applied to investigate energy transfer processes in luminescence. By simulating the static distribution of the Donor-Accepter transfer rates,we have got the decay of donor luminescence in static transfer model. The result coincides with that of Inokuti-Hirayama model. The influence of D—D transfer to donor luminescence decay is simulated and discussed for both the cases of independent and correlated D—D and D—A transfer rates.