On the use of relative line intensities of forbidden and allowed components of several HeI lines for electric field measurements

In this Letter we propose a method for electric field measurements based on intensity ratio of forbidden and allowed helium lines. HeI 402.6 nm, HeI 447.1 nm, and HeI 492.1 lines and their forbidden components are used for the measurement of electric field strength in the cathode region of the abnormal glow discharge in helium-hydrogen mixture. Electric filed strength was independently determined using polarization spectroscopy of Hβ line and then compared with electric filed strength obtained from relative intensity of HeI forbidden and allowed lines.     

Influence of carrier cations on the intensity of spectral lines of microelements in atomic-emission spectral analysis

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 1, pp. 18–21, January, 1991.     

Absolute Raman intensity measurements and determination of the vibrational second hyperpolarizability of adamantyl endcapped polyynes

Linear sp‐carbon polyynes are ideal molecules for the direct investigation of the physical properties of one‐dimensional conjugated systems. Traditionally, the main obstacle to the study of these systems has been their instability under normal laboratory conditions. Thanks to improved chemical syntheses, a broadened range of polyynes is now available for study, including the hydrocarbon series endcapped with adamantyl groups, Ad[n]. In this work, the quantitative Raman spectroscopic analysis is reported for each member of this homologous series. The Raman scattering intensities corresponding to the major features of the polyyne segment (i.e., the effective conjugation coordinate or Я lines) are then used to evaluate the nonlinear optical (NLO) behavior via determination of the vibrational contribution to the second hyperpolarizability (γ_vib). This study shows that γ_vib values as a function of length are of the same order of magnitude as those arising from the electronic contribution to the molecular second hyperpolarizability, γ_ele, as reported for triisopropylsilyl polyynes, TIPS[n], using the differential optical Kerr effect technique. The nonlinear response for Ad[n] polyynes, supported by the analogous response for TIPS[n] polyynes, confirms that linear sp‐carbon molecules have large second hyperpolarizabilities that show a power‐law increase in γ‐values versus length that is larger than other known π‐conjugated systems, such as polyenes. Furthermore, the NLO response of polyynes versus length approaches the theoretical limit described by Kuzyk more closely than other conjugated organic oligomers. Copyright © 2012 John Wiley & Sons, Ltd.     

On the most accurate measurements of the wavelengths of X-ray spectral lines

The paper discusses the influence of statistical errors in measuring the intensity of a spectral line on the exact determination of its wavelength. Using simplifying assumptions, it is shown that the relative error in measuring the wavelengths of spectral lines of the same type, caused by the statistical character of X-ray intensity measurements and by the influence of the true width of the spectral line, is practically constant under the same conditions, i.e. it is independent of the lattice parameters of the crystals used and of the wavelength of the spectral line. It seems that the latest exact measurements of Bearden confirm this result.The greatest care should therefore be devoted to the neighbourhood of inflection points of the curve representing the spectral line profile when making exact measurements of the spectral position of the lines.The author heartily thanks Professor M. A. Blochin for valuable remarks on this work.     

Narrowing of spectral lines beyond the natural or dephasing line width

Transient excitation and gated or delayed observation provides a narrowing of the inherent line width of the transition. Possible experimental one- and two-photon systems are discussed and the loss of signal with line narrowing is calculated. The general case of lines broadened by dephasing processes is treated. Contact is made with the line narrowing in recent Raman type experiments.     

Sequential spectral lines and intensity distribution in electronic-vibrational bands of free polyatomic molecules

The intensity distribution, the spectral band profile, and the temperature dependences of spectral characteristics of bands in the electronic-vibrational (vibronic) spectra of free polyatomic molecules are studied based on the concept of sequential lines (SLs) as constituent elements of these bands. It is shown that the intensity distribution in a separate electronic-vibrational band is defined by the convolution of an SL profile with the frequency distribution function of sequential transitions. Expressions for the intensity distribution in homogeneously and inhomogeneously broadened electronic-vibrational bands are derived, and specific features of their spectral behavior are determined. Using the latter results, distinguishing features or criteria of the character of broadening of the vibronic spectra of free polyatomic molecules are formulated.     

Analysis of collision-broadened and overlapped spectral lines to obtain individual line parameters

Estimates of the statistical errors, correlations among the various fitting parameters and the accuracy of a simple approximation to a Voigt line profile are discussed in relation to the separation between adjacent lines. The computational procedure combined a series approximation with a nonlinear least-squares fitting routine to accurately fit the line profile and estimate the errors. Data were obtained for both simulated and experimental spectra as a means of testing the accuracy of the formalism and the effect of line separation.     

New laser lines from optically pumped CH3OH: measurements and assignments

New CW FIR laser lines from optically pumped CH₃OH are reported. Experimental values for wavelength, polarization and pump offsets are given. Lines assignments are proposed. New experimental results and possible assignments are also given for previously reported lines.     

New FIR laser lines and frequency measurements for optically pumped CD3OH

Twenty new cw FIR laser lines in CD₃OH, optically pumped by a CO₂ laser, are reported. The frequencies of 39 of the stronger laser lines were measured relative to stabilized CO₂ lasers with a fractional uncertainty, as determined by the reproducibility of the FIR frequency itself, of 2 parts in 10⁷.Contribution of the U.S. Government, not subject to copyright.     

Determination of the relative and absolute intensities of self-absorbing and self-reversing spectral lines of arc discharges

The effect of self-reversal and self-absorption in spectral lines upon measurements of the relative and absolute intensities in arc discharges is treated, based on the theory of Cowan and Duke. It is shown that the self-absorption described by the theory of Cowan and Duke leads to sensible values for the source temperatures measured through relative intensities. A technique of measuring the absolute intensity of self-reversing lines is suggested.     

Absolute integrated intensity and individual line parameters for the 6·2μ band of NO2

The absolute integrated intensity of the 6·2μ band of NO₂ at 40°C was determined from quantitative spectra at ~ 10 cm^?1 resolution by the spectral band model technique. A value of 1430±300 cm^?2 atm^?1 was obtained. Individual line parameters, positions, intensities and ground state energies were derived, and line-by-line calculations were compared with the band model results and with the quantitative spectra obtained at ~ 0·5 cm^?1 resolution.     

均匀带电线与接地导体薄圆筒内的等势线与电场线方程

利用电象法和解析函数的规律,得出均匀带电线与接地薄导体圆筒内的电势和电场强度表达式,并给出了等势线与电场线方程.     

Linewidth and relative intensity noise measurements of longitudinal modes in ultrahigh-speed mode-locked laser diodes

The longitudinal linewidth and corresponding relative intensity noise (RIN) of 10- and 40-GHz mode-locked laser diodes are measured for the first time to our knowledge. It is shown that the cavity Q value is a dominant parameter of the linewidth. It is also shown that the linewidth of the individual modes is almost constant. This means that the phase noise of each mode is almost the same in the mode-locked condition. The RIN value is larger for modes that are distant from the center longitudinal mode. This mode dependence is a consequence of the mode partition noise.