We have developed a model for calculating saturated absorption spectra for dipole transitions in multi-level atoms. Using a semiclassical density matrix formalism, we derive a set of coupled differential equations for the internal state of the atom in a standing wave light field. The equations are solved using standard integration techniques. The absorption at each laser detuning is found from ...

Optical absorption spectra from silicon-implanted silica slides are shown to contain features due to optical interference. These features, which result from the modified refractive index profile produced by the implant, can readily lead to misinterpretation of absorption spectra. To demonstrate the importance of such effects, silica samples were implanted with 80, 400, and 600 keV Si ions to fl...

We present an extended analysis of the high dispersion IUE spectra of SN 1993J in M 81, based on the improved data in the IUE final archive. Eight interstellar absorption components can be identified in the velocity range from −200 km s to +200 km s. Column densities are determined for Fe II, Mg I, Mg II, O I, S II, Si II, and Zn II. From the ion ratios, we estimate electron densities and tempe...

Hot methane is found in many “cool” sub-stellar astronomical sources including brown dwarfs and exoplanets, as well as in combustion environments on Earth. We report on the first high-resolution laboratory absorption spectra of hot methane at temperatures up to 1200 K. Our observations are compared to the latest theoretical spectral predictions and recent brown dwarf spectra. The expectation th...

The terahertz (THz) spectra of rapeseed leaves with different water content (WC) were investigated. The transmission and absorption spectra in the range of 0.3-2 THz were measured by using THz time-domain spectroscopy. The mean transmittance and absorption coefficients were applied to analyze the change regulation of WC. In addition, the Savitzky-Golay method was performed to preprocess the spe...

in this work, we report, optical properties of cd1-xsnxte quantum dots (x= 0.05, 0.10 and 0.15) synthesized in water using thioglycolic acid (tga) as a modifier agent. the optical characterization of the samples was performed through absorption (uv) and photoluminescence spectra (pl). a red shift absorption and fluorescent emission peaks was observed which can be related to the increase of nano...

calcium fluoride nanoparticles with special amount of cerium ion (%1) were synthesized by coprecipitation. fourier transforms infrared spectroscopy (ftir), x-ray diffraction (xrd), absorption and photoluminescence (pl) from caf2ce nanoparticles has been investigated. ftir spectra reveal that there are some amounts of oh, no3 and other organic functional groups on the particle surfaces before th...

The M a and M ~ emission spectra and the M IV and M v absorption spectra have been stud~ed for th~ r~re earth elements. It is conclusively shown that the complicated multiplet structure o~served .1I~ the enusslOn spectra is not real emission structure but is, inst~ad, pro?u~ed b! sample self-absorption. This Is.demonstrated by observing the emission spectra over wIde vanatlOns In take-?ff. angl...