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Line widths of (N-14)H3 and (N-15)H3 applicable to planetary atmospheric observations
The collision-broadened half-widths of sP(1,0), sP(3,2), sP(4,1), sP(4,2), and sP(4,3) in the v2 sup s-fundamental bands of (N-14)H3 and (N-15)H3 have been measured at 198, 245, and 295 K employing the Doppler-limited spectral resolution of a tunable diode laser spectrometer. The temperature dependence of the collision-broadened half-widths of these lines broadened by H2 and N2 has been determined. In addition, we have also measured the air-broadened line widths of all of these lines at 295 K and the half-width of the sP(3,2) line of (N-15)H3 broadened by (N-14)H3 at 198, 245, and 295 K.
Measurement of line widths of CO of planetary interest at low temperatures
Self-broadened, air-broadened and CO2-broadened half-widths of lines R(0) through R(16) in the CO fundamental have been measured at 100 K (self-broadening only), 200 K, 250 K and 300 K using the Ladenburg-Reiche curve-of-growth. The relation which we found previously for the nitrogen-broadened half-widths of R(0), R(8), and R(16), is shown to be valid for all of the line widths measured in the present study.
The dynamical properties of the solar corona from intensities and line widths of EUV forbidden lines of Si VIII, Fe XI, and Fe XII
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Optically thick line widths in pyrotechnic flares
Experimentally determined sodium line widths for pyrotechnic flares are compared with simple analytical, optically-thick-line-shape calculations. Three ambient pressure levels are considered (760, 150 and 30 torr) for three different flare compositions. The measured line widths range from 1.3 to 481 A. The analytic procedure emphasizes the Lorentz line shape as observed under optically-thick conditions. Calculated widths are in good agreement with the measured values over the entire range.
Measurements of collision-broadened line widths in the nu4-fundamental band of (C-12)H4 at low temperatures
Collision-broadened half-widths of several lines in the nu4 fundamental band of (C-12)H4 have been measured at low temperatures between 130 and 295 K using a tunable diode laser and the sweep integration technique. The broadening gases are H2, N2, He, and Ar. The temperature dependence of the measured line widths is described in terms of an exponent n, which is shown not only to be different for each broadening gas but also to depend upon the tetrahedral symmetry identification of the lines of CH4.
Tunable diode laser measurements of line widths in the nu1-fundamental band of (N-14)2(O-16) at atmospheric temperatures
A tunable diode-laser spectrometer and a low-temperature absorption cell have been employed to measure the N2-broadened and O2-broadened half-widths of rotational lines in the nu1 fundamental band of (N-14)2(O-16) at 185, 235, 263, and 295 K. The temperature dependence of the line widths has been observed to be practically identical, thereby leading to the suggestion that air-broadening would exhibit the same dependence.
Strong-field cyclotron scattering. I - Scattering amplitudes and natural line width
The introduction of resonance line width into the QED cyclotron scattering amplitudes is considered. It is shown that the width arises from loop corrections to the electron propagator, which also bring about shifts in the Landau energy levels. A formalism is developed that allows the dressed electron propagator to be derived. It is shown that the states of Herold et al. (1982) and of Sokolov and Ternov (1968), which diagonalize the component of the magnetic moment operator parallel to the external magnetic field, are appropriate for calculation of the scattering amplitudes, whereas the states of Johnson and Lippmann (1949) are not. In addition, it is shown that the Breit-Wigner broadening approximation E tends to E - i(Gamma)/2 is consistent with the perturbation-theoretic order of the calculation, if the former basis states are chosen, but not the latter.
Effect of nonlinear interactions on p-mode frequencies and line widths
We calculate the effect of nonlinear interactions among solar acoustic modes upon the modal frequencies and energy loss rates (or line widths). The frequency shift for a radial p-mode of frequency 3 mHz is found to be about -0.5 microHz. The magnitude of nonlinear frequency shift increases more rapidly with frequency than the inverse mode mass (mode mass is defined as the ratio of energy in the mode to its surface velocity amplitude squared). This frequency shift is primarily due to nonresonant three-mode interactions and is dominated by high l surface gravity waves (f-modes) and p-modes. The line width of a radial p-mode of frequency 3 mHz, due to resonant nonlinear interactions, is about 0.3 microHz. This result is consistent with that of Kumar and Goldreich (1989). We also find, in agreement with these authors, that the most important nonlinear interactions of trapped p-modes involve f-modes and high-frequency p-modes (frequency greater than about 5 mHz) which propagate in the solar photosphere. Thus, using the arguments advanced by Kumar & Goldreich (1989), we conclude that nonlinear couplings cannot saturate the overstable solar p-modes at their small observed amplitudes. Both the nonlinear frequency shifts and line widths, at a fixed frequency, are proportional to the inverse of mode mass which for modes of degree greater than about 100 is approximately l(exp 0.8). Therefore, the frequency of an f-mode of l = 1000, due to nonlinear interactions, is decreased by approximately 0.4%.
Comparison of second-order spectral line widths formulae
Frequently used second-order spectral line width formulae from the projector operator and kinetic theory methods have not been formally compared previously. Here it is shown that a systematic second-order expansion of the projection operator expression including initial correlations agrees with the second-order kinetic theory result. The agreement assumes a common approximation in the projector operator method that introduces a screened radiator–perturber interaction to account for neglected electron–electron correlations. On the other hand, it is shown that the usual width expression from the projection operator approach neglecting initial correlations differs from kinetic theory. The differences, however, are at least third order in the radiator–perturber interaction. The comparisons suggest using the more compact width expression from kinetic theory, which includes initial correlations and a systematic screening of the radiator–perturber interactions, as the starting point for second-order width calculations.
Measurements of collision-broadened line widths in the 7.66-micron band of (C-12)H4 at temperatures relevant to the atmosphere
A tunable diode laser spectrometer is used to measure the collision-broadened half widths of spectral lines in the fundamental band of (C-12)H4 at 7.66 microns at temperatures between 130 and 295 K. Consideration is given to O2-, N2-, and air-broadened half widths. The temperature dependence of the measured line widths is examined.
2.5 MHz Line-Width High-energy, 2 Micrometer Coherent Wind Lidar Transmitter
2 micron solid-state lasers are the primary choice for coherent Doppler wind detection. As wind lidars, they are used for wake vortex and clear air turbulence detection providing air transport safety. In addition, 2 micron lasers are one of the candidates for CO2 detection lidars. The rich CO2 absorption line around 2 micron, combined with the long upper state life of time, has made Ho based 2 micron lasers a viable candidate for CO2 sensing DIAL instrument. The design and fabrication of a compact coherent laser radar transmitter for Troposphere wind sensing is under way. This system is hardened for ground as well as airborne applications. As a transmitter for a coherent wind lidar, this laser has stringent spectral line width and beam quality requirements. Although the absolute wavelength does not have to be fixed for wind detection, to maximize return signal, the output wavelength should avoid atmospheric CO2 and H2O absorption lines. The base line laser material is Ho:Tm:LuLF which is an isomorph of Ho:Tm:YLF. LuLF produces 20% more output power than Ho:Tm:YLF. In these materials the Tm absorption cross-section, the Ho emission cross-section, the Tm to Ho energy transfer parameters and the Ho (sup 5) I (sub 7) radiative life time are all identical. However, the improved performance of the LuLF is attributed to the lower thermal population in the (sup 5) I (sub 8) manifold. It also provides higher normal mode to Q-switch conversion than YLF at high pump energy indicating a lower up-conversion. The laser architecture is composed of a seed laser, a ring oscillator, and a double pass amplifier. The seed laser is a single longitudinal mode with a line width of 13 KHz. The 100mJ class oscillator is stretched to 3 meters to accommodate the line-width requirement without compromising the range resolution of the instrument. The amplifier is double passed to produce greater than 300mJ energy.
Fabry-Perot interferometers with electronic determination of Doppler line widths.
Fabry-Perot interferometers with electronic determination of Doppler line widths, discussing effect of hyperfine and isotopic structure
Infrared line widths at planetary atmospheric temperatures
Recent theoretical models and measurements of the variation of collision-broadened line width with temperature in the infrared are discussed for temperatures relevant to planetary atmospheres. The present review is restricted to lines broadened by H2, N2, O2, CO2, and He, the lines formed in the atmospheres of Jupiter, Saturn, Uranus, and Neptune. The design for a low-temperature absorption cell consisting of a nickel-coated copper tube is described. The lack of an adequate theoretical model for variation of the collision-broadened line width with temperature in terms of the molecular constants of the colliding partners is pointed out.
An Empirical Expression for the Line Widths of Ammonia
The hydrogen-broadened line widths of 116 (sup 14)NH(sub 3) ground state transitions have been measured at 0.006 cm(sup -1) resolution using a Bruker spectrometer in the 24 to 210 cm(sup -1) region. The rotational variation of the experimental widths with J(sup '),K(sup ') = 1,0 to 10,10 has been reproduced to 2.4 % using an heuristically derived expression of the form gamma = a(sub 0) + a(sub 1) J(sup ') + a (sub 2) K(sup ') + a(sub 3) J(sup ')(sup 2) + a(sub 4) J(sup ') K(sup ') where J(sup ') and K(sup ') are the lower state symmetric top quantum numbers. This function has also been applied to the measured widths of the 58 transitions of nu(sub 1) at 3 (micro)m, each broadened by N(sub 2), O(sub 2), Ar, H(sub 2), and He. The rms of the observed minus calculated widths are 5% or better for the five foreign broadeners. The values of the fitted constants suggest that for some broadeners the expression might also be written as gamma = a(sub 0) + b(sub 1) J(sup ') + b(sub 2)(J(sup ' )- K(sup ')) + b(sub 3) J(sup ')(J(sup ') - K(sup ')) .
The role of higher-multipolar and repulsive forces in the calculation of collision-broadened line-widths of linear molecules
Collision-broadened line widths in CO-CO2 and CO-O2 collisions have been calculated by incorporating interactions due to octopoles and hexadecapoles and short-range repulsive interactions into Anderson's (1949) theory. It is shown how these higher-order interactions can be manipulated to yield good agreement with experimental data. A critical evaluation of this totally empirical manipulation suggests that a thorough revision of the theory is required for all but simple dipole-dipole interactions. In the process of the evaluation, the values of the multipole moments are discussed.
Rotational interpretation of recombination line widths in the galactic nucleus
The widths of the radio recombination lines observed in the direction of the galactic center are interpreted as due to pure rotation. This interpretation leads to a mass estimate for the inner 1.6-pc region of our Galaxy. It is noted that recent observations of M 31 suggest the existence of a distinct dynamic entity at its center - the nucleus. The rotational interpretation of the recombination line widths is shown to be consistent with the existence of a nucleus at the center of our own Galaxy which is similar in nature to the nucleus of M 31.
Line width of the solar EUV He I resonance emissions at 584 and 537 A
Instrumentation was carried aloft on a Black Brant rocket in August 1982 to gather spectrometry on the solar He I resonance lines. The payload consisted of a He spectrometer which furnished 11 readings at FWHM of close to 97 and 132 mA for the 584 and 537 a lines, respectively. The results indicated a variation of the solar line width that was inversely correlated with solar activity and with the solar EUV flux. Further studies of the 522 A line are recommended to detect any unidentified first order solar emissions close to or within the absorption profile of the 537 A line that contributed to the observed line width.