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For the efficient operation of a cavity ringdown spectroscopy (CRDS) system utilized with a continuous-wave (cw) laser, we numerically analyze the coupling efficiency of a cw laser to a ringdown cavity in terms of changes in the scanning rate, the laser linewidth, and the mirror reflectivity. We also demonstrate a new simple design for a CRDS system that can produce a CRDS signal with only a piezoelectric transducer (PZT), without the acousto-optic modulator that is usually adopted to switch off the cw laser beam that enters the cavity. Furthermore, we investigate the feasibility of the cw CRDS technique with a fast-scanning PZT by recording a CRDS spectrum of acetylene overtones. The detection sensitivity that corresponds to the noise-equivalent absorption is found to be [approximately]3 x [10.sup.-9]/cm.

We determined the instrument function or the response function of a grating spectrometer with finite slit widths in conditions of partial coherent illumination, by using a spectral-interference technique with white light. A Michelson interferometer of variable path delay is used to produce the spectral-interference fringes of required spacing. By deconvolution of the spectral visibility data for various exit and entrance slit widths, we have determined the exact form and frequency width of the instrument function for the spectrometer as well as the working region of the spectrometer for the least distorted output spectrum. Key words: Instrument function, spectral interference, white-light interferometry.

Time-resolved microwave conductivity (TRMC) measurements, giving intrinsic charge carrier mobility in highly ordered structures without an electrode attached are used to investigate photoinduced transient conductivity of pentacene thin films prepared by thermal vapor deposition. The TRMC technique is the only technique revealing the intrinsic potentials of mobility in materials that is supported by complete experimental and quantitative procedures not based on any assumptions.

Atomistic tight-binding method and multiband effective mass theory were used to interpret optical spectra of CdS nanocrystals. Both methods correctly described the energy splitting between the two lowered optically active transitions and their relative strengths, proving the same labeling of the two main adsorption peaks of the spectrum.

The temperature-induced transformation of inhomogeneous spectra of an optical probe can reflect structural changes of the biphenyl crystal are demonstrated. This can be possible if there is good enough accommodation of quest (probe) molecules into the host (biphenyl) crystal and close to the pure biphenyl values for critical parameters can also be obtained.

Pressure and temperature effects on (quasi) homogenous optical spectra of dyes in solvent glasses and polymers were investigated by hole burning. The relevance of the Lennard-Jones model approach, with respect to temperature and pressure broadening and linear electron-phonon coupling is discussed in short.

The intermediate neglect of differential overlap method for optical spectroscopy (INDO/S0) is used by the spin-orbit configuration interaction (SOCI) calculations to investigate the ground-state spin-orbit splittings in V2 plus, VNb plus and Nb2 plus. Analysis of correlation effects in the INDO/S model indicates that a charge-iterative method could be more effective for systematically correlated semiempirical calculations on metal cluster ions.