Substantiation of the mechanism of biphoton nonresonance excitation of molecules of bacteriochlorophyll of purple bacteria by femtosecond pulses

Abstract

In a series of published experimental works, there has been observed nonresonance biphoton excitation, by femtosecond IR pulses (1250–1500 nm) of molecules of bacteriochlorophyll-a and the pigment in the composition of light-absorbing natural “antenna” complexes of photosynthesizing purple bacteria. The authors of these works believe that IR quanta excite hypothetical forbidden levels of pigments of these bacteria in the dual frequency range of 625–750 nm. In this study, an alternative mechanism of intramolecular electron transport apparently responsible for this phenomenon is suggested and substantiated. The mechanism should manifest itself in powerful electric fields, which are achieved in the pulses of picofemtosecond lasers.