V. I. Serdyukov

LED-Based Fourier Transform Spectroscopy: the HD16O Absorption Spectrum in the Range of 11200–12400 cm−1

The vibrational—rotational spectrum of the HD16O molecule is studied within the range of 11200−12400 cm−1. The spectrum is recorded by an IFS-125M Fourier spectrometer with a resolution of 0.05 cm−1. The measurements are performed using a multipass White cell. A light-emitting diode is used as a radiation source. The signal-to-noise ratio was about 104. The centers, intensities, and half-widths of the spectral lines are determined by fitting to the experimental data by the least-squares method. A linelist containing more than 1500 lines is created. The results obtained are compared with the experimental data of other authors.

Study of the Water Vapor Absorption Spectrum in the Visible Spectral Region from 19480 to 20500 cm−1

The vibrational-rotational absorption spectrum of water vapor was recorded and analyzed in the visible spectral region from 19480 to 20500 cm−1. The measurements were carried out using an IFS-125M Fourier spectrometer with a resolution of 0.05 cm−1 at a pressure of 26.3 mbar, a temperature of (24 ± 1)°C, and optical path 24 m. We used a multipass White cell with a base length of 60 cm. A light-emitting diode was used as a radiation source. The signal-to-noise ratio was about 20000. The list of more than 420 lines has been compiled as a result of the analysis the spectrum, which includes line centers, intensities, and quantum vibrational-rotational numbers. More than 220 vibrational-rotational energy levels of 21 upper vibrational states have been determined from the experimental data.

Broadening and Shift of the Methane Absorption Lines in the 11000–11400 cm–1 Region

Absorption spectra of methane in the 11000–11400 cm–1 spectral region were recorded with an IFS-125M Fourier spectrometer at pressures from 11 to 100 mbar, a room temperature, and a spectral resolution of 0.03 cm–1. A multipass cell 60 cm long with 44 passes provided a total path length of 2640 cm and threshold sensitivity to absorption of about 10–8 cm–1. Line centers, intensities, self-broadening, and selfshift coefficients of methane lines were determined by fitting Voigt profile parameters.

The absorption spectrum of D 2 O in the region of 0.97 μm: the 3ν 1 + ν 3 vibrational–rotational band

The vibrational–rotational absorption spectrum of D2O in the range from 10 120 to 10 450 cm–1 is recorded on a Fourier transform spectrometer with a resolution of 0.05 cm–1. The measurements were performed using a multipass White cell with an optical path length of 24 m. A light-emitting diode with brightness higher than that of other devices was used as a radiation source. The signal-to-noise ratio was about 104. The spectrum is interpreted as consisting of lines of more than 400 transitions. The spectral characteristics of lines (centers, intensities, and half widths) are determined by fitting the Voigt profile parameters to experimental data by the least-squares method. The intensities of lines and the experimental rotational energy levels of the (301) vibrational state of the D216O molecule with high rotational quantum numbers are determined for the first time.

Dependence of H2O-N2 broadening coefficients on the vibrational quantum numbers

Line broadening in the case of H2O-N2 colliding system only slightly depend on vibrational quantum indices. The largest difference in the broadening coefficients of different bands is as small as several percent. Usually the halfwidths obtained for only one band is extrapolated to other vibrational bands. Indeed, in the case of low-lying states the vibrational amplitudes are usually small in comparison to the equilibrium distances between the atoms. However, for transitions to highly excited states, the intra-molecular motion cannot be treated as small amplitude vibrations, and as a consequence, corrections due to the intra-molecular interactions are large. The vibrational dependence of the line widths was studied by a high resolution Fourier-transform spectrometer IFS-125M. Line-broadening and line-shifting coefficients derived from the fitting were compared to calculated data.

H2O self-broadening coefficients of rotation-vibration lines in the 15 500 – 16 000 cm-1 region

Line broadening coefficients of the Н2О-Н2О system were investigated in the region 15500 – 16000 cm-1 using a high resolution Fourier-transform spectrometer IFS-125M. The White type multipass absorption cell with a basic length of 60 cm was used. Least-square-fitting algorithm WXSPE was used to retrieve of the spectroscopic parameters from measured spectral data set. Calculations of self-broadening are performed using a semi-empirical approach. This method is further developed by using anharmonic wavefunctions in the estimates of line profiles. This approach explicitly takes into account all scattering channels induced by collisions. Calculated data are in a good agreement with the measured ones.

High-temperature spectrum of water vapor in the 1.2 spectral region

This work is devoted to the water vapor spectrum analysis in the near-IR region. The water vapor spectrum was studied using intracavity laser spectrometer in 8250-9100 cm-1 region with the spectral resolution of 0.05 cm-1 and at temperature of 1000 K. The spectra identification was done. More than 10 vibrational bands were recorded and analyzed.

Intracavity laser spectroscopy of water vapor at high temperature

The main purpose of this study is to report measurements of H216O line positions at the temperature of 1300 K in 1.06 micrometers region. The H2O frequency measurements were used to obtain values of rotational energy levels for the (111) and (012) vibrational states for J < 18.

Intracavity laser spectroscopy of molecules at high temperatures

Spectra of water vapor and carbon dioxide isotopomeres were recorded using ICL-spectrometers at high temperature up to 1350K. The transitions beginning the rotational levels with high J-quantum numbers as well as hot bands were recorded.

INTRACAVITY LASER SPECTROSCOPY OF EXCITED ATOMS AND MOLECULES

The fine structure of highly excited atomic and molecular states has been investigated suing high sensitive intracavity laser spectrometers with spectral resolution within the interval from 0.018 to 0.05 cm-1 and at minimum detectable absorption coefficients in the 10-7 - 10-8 cm-1 range in the visible and photographic infrared regions.