Two-photon interference in the presence of absorption

Experiments on two-photon interference are discussed in the case when there is absorption of all the modes participating in the process of spontaneous parametric down-conversion (SPDC) of light. The objects of investigation are 10-to 80-Å-thick ultrathin gold films deposited on fused-silica substrates. Conditions are determined under which the effect of absorption of the signal and pump waves on the interference pattern is small. It is shown that, under these conditions, the visibility of the interference pattern and the shape of the frequency-angular spectrum at the signal frequency are determined by the optical parameters of the medium at the idler frequency, which belongs to the near-infrared region.     

Chemical properties of marine terpenoids. 1. Some reactions of (6S,10R)-10-bromo-3,11,11-trimethyl-7-methylidenespiro[5,5]undec-2-en-4-one,a sesquiterpenoid from the sea hare Aplysia dactylomela

The structures of products obtained by reductive debromination and CF₃COOH- and KOH-induced transformations of natural chamigrane-type sesquiterpenoid (6S,10R)-10-bromo-3,11,11-trimethyl-7-methylidenespiro[5,5]undec-2-en-4-one (dactylone) isolated from the sea hare Aplysia dactylomela were analyzed. The absolute configurations of the reaction products were established by CD spectra taking into account the configuration of the starting dactylone.     

Nonsteady motion of a dropping compressible liquid in pipes under different laws of friction

Certain cases of nonsteady motion of a dropping compressible liquid with different laws of friction in conduits (in particular, in main oil pipelines) are considered. Results are presented of a solution of a number of problems of unsteady motion of a dropping liquid in pipes with a square law of resistance and for regimes characteristic of hydraulically smooth pipes, obtained numerically by the method of finite differences (method of nets). A comparison is made to results obtained by linearizing the term containing the square-law friction according to a previous [1] technique. Deviations of the parameters of nonsteady flows for given laws of resistance are studied.Translated from Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 1, pp. 87–94, January–February, 1976.