At high latitude the hard electron precipitation associated with auroral activity is a major source of ionization for the D-region, one consequence being the absorption of radio waves. Direct measurements of the D-region electron density are not readily available, however. This paper investigates the relationship between the electron density at altitudes between 100 and 70 km and the total radi...

We report a theoretical–experimental investigation on elastic electron scattering by acetaldehyde (CH $$_3$$ CHO) in the 0.5–800 eV energy range. Theoretically, Padé approximation and single-center partial-wave expansion method were applied to solve Lippmann–Schwinger equation, whereas molecular complex optical potential was used describe electron–molecule interaction. Calculations independent-...

We investigate the absorption spectrum of a laser driven V system in which one of the upper levels is metastable. If the Rabi frequency of the laser driving the metastable transition is suuciently small we nd an extremely narrow peak in the stationary absorption spectrum of a weak probe on the strong transition. We give analytical expressions approximating the stationary absorption spectrum. Th...

We investigate theoretically electron dynamics under a VUV attosecond pulse train which has a controlled phase delay with respect to an additional strong infrared laser field. Using the strong field approximation and the fact that the attosecond pulse is short compared to the excited electron dynamics, we arrive at a minimal analytical model for the kinetic energy distribution of the electron a...

background: flow cytometry is a rapid, sensitive, and reliable method for determination of bacterial viability. here we assayed the capability of flow cytometry to detect helicobacter pylori viable cells in both forms of spiral and coccoid. methods: viable bacteria stained with rhodamin 123 and fluoresced with laser beam of 488nm. the rate of rh123 absorption was determined in both forms of bac...

Low-temperature photoluminescence-excitation spectra are studied in an n-type modulation-doped T-shaped single quantum wire with a gate to tune electron densities. With a nondegenerate one-dimensional (1D) electron gas, the band-edge absorption exhibits a sharp peak structure induced by the 1D density of states. When the dense 1D electron gas is degenerate at a low temperature, we observe a Fer...

An experimental demonstration of a dynamic decrease of the optical band gap of bulk n-InSb induced by picosecond, midinfrared laser pulses is reported. This occurs as a result of laser heating of the quiescent electron distribution by free-carrier absorption. The hot electrons vacate low-energy states near the conductionband minimum, unblocking terminal states for two-photon absorption across t...