Nonequilibrium spectral diffusion due to laser heating in stimulated photon echo spectroscopy of low temperature glasses

A quantitative theory is developed, which accounts for heating artifacts in three-pulse photon echo (3PE) experiments. The heat diffusion equation is solved and the average value of the temperature in the focal volume of the laser is determined as a function of the 3PE waiting time. This temperature is used in the framework of nonequilibrium spectral diffusion theory to calculate the effective homogeneous linewidth of an ensemble of probe molecules embedded in an amorphous host. The theory fits recently observed plateaus and bumps without introducing a gap in the distribution function of flip rates of the two-level systems or any other major modification of the standard tunneling model.Comment: 10 pages, Revtex, 6 eps-figures, accepted for publication in Phys. Rev.

Optical free induction decay of molecules undergoing radiative and radiationless relaxation

In this paper we examine the effect of radiative and radiationless processes on optical free induction decay (OFID) in singlet–singlet transitions of molecules in the condensed phase. The main conclusion is that the applicability of OFID to molecular singlet–singlet transitions is severely limited by the presence of an intermediate triplet state, which quite often forms a bottleneck in the optical pumping cycle. Using the theoretically derived formulas for the OFID signal, we examine the feasibility of OFID experiments on the mixed crystals of porphin in n-octane and naphthalene in durene and conclude that such experiments, if at all fruitful, would be difficult to execute. We re-evaluate the reported OFID results of pentacene in p-terphenyl and obtain for the lowest 1B2u ← 1A1g transition a dipole moment of 0.9 ± 0.3 D.

Study guide "Economic theory" for students of the specialties 25 "Economics"

The study guide reflects the issues of the formation of economic theory based on the study of the achievements of domestic and world economic thought. The main issues of models and the state of markets, firm costs, pricing methods and many others are considered in order to form basic economic knowledge of students. The guide is addressed to students of the 1st stage of higher education, specialties 25 "Economics"