DIODE LASER SPECTRA OF THE υ2\upsilon_{2} BAND OF 15NH3^{15}NH_{3}

The $\upsilon_{2}$ band of $^{15}NH_{3}$ in the $927-1087 cm^{-1}$ region has been studied by using a tunable diode laser. Spectra were recorded using a two-channel system in which one part of the diode laser radiation passed through the gaseous sample while another part was simultaneously mixed with radiation from a $CO_{2}$ laser. Using this technique, lines within $\pm 8 GHz$ of a $CO_{2}$ laser line have been measured to an accuracy of 13 MHz. Lines in both the antisymmetric-to-symmetric and symmetric-to-antisymmetric portions of the $\upsilon_{2}$ band have been measured and assigned. Other lines, probably associated with the $2\upsilon_{2} - \upsilon_{2}$ band of $^{15}NH_{3}$, have been measured

THE DIODE LASER HETERODYNE SPECTRUM OF CDF3CDF_{3}

$^{1}$ M. S. Tobin, R. P. Leavitt, T. W. Daley, and W. G. Trueheart, contributed paper, this conference. $^{2} E$. Ibisch and U. Andresen, Z. Naturforch $35a, 1020-1029 (1981)$.Author Institution: Army Electronics Research and Development command, Harry Diamond LaboratoriesThe IR spectrum of the $\nu_{5}$ band of $CDF_{3}$ has been obtained by using a diode laser heterodyne spectrometer. Hundreds of lines in the neighborhood of the $10R(J) CO_{2}$ laser Lines have been measured to Within 6 MHz accuracy. The interesting feature of $K = 3$ splitting is observable in the ${^{P}}Q(J,3)$ branch. This IR heterodyne data complements the $\nu_{5}$ rotational data of Ref. 1 and the laser Stark data of Ref. 2

DIODE LASER HETERODYNE SPECTROSCOPY ON THE ν1\nu_{1} BAND OF SULFUR DIOXIDE

$^{1}$ A.R. Calloway and E.J. Danielewicz, Private Communication $^{2}$ G.J. Simonis, Private Communication.Author Institution:Diode laser heterodyne techniques have been used to study the extreme P-branch of the $\nu_{1}$ band of $^{32}S^{16}O_{2}$. Fifty-five high J, K absorption lines have been measured with an accuracy of $\pm 6 MHz$. These data were combined with previously measured ground state and excited state microwave data to obtain an improved set of molecular constants for the $\nu_{1}$ state. The value obtained for the band center, $\nu_{0}$ was 1151.71352(31) \mbox{cm}^{-1}. Sub-millimeter laser transitions have recently been observed when the $\nu_{1}$ band is pumped with a $CO_{2}$ $laser^{1,2}$. The constants obtained have been used to assign these high quantum number transitions

INFRARED DIODE LASER HETERODYNE MEASUREMENTS ON 14NH3^{14}NH_{3}

$^{1}$S. Urban et al., J. Mol. Spectrosc. 79, 455--495 (1980).Author Institution:The frequencies of 32 obsorption lines of $^{14}NH_{3}$ in the 9 and 10 micrometer region were measured by use of a diode laser heterodyne spectrometer. The frequencies of 11 additional IR transitions were determined from these measured transitions by forming combination differences with measured inversion and rotation-inversion transitions [1]. The precision of our measurement was about 3 MHz or 1 \times 10^{-4} \mbox{cm}^{-1}. When referred to previous measurements by other ultra-high resolution techniques on 12 lines that have been reported accurate to 2 \times 10^{-4} \mbox{cm}^{-1} or better, our corresponding measurements have a standard deviation of 1.1 \times 10^{-4} \mbox{cm}^{-1}. After an allowance for systematic errors, we believe our measurements to be accurate to 6 MHz. When referred to our new measurements, the standard deviation of the frequencies of 19 transitions previously measured by etalon calibration is 6 \times 10^{-3} \mbox{cm}^{-1}

DIODE LASER HETRODYNE SPECTYOSCOPY ON THE ν4\nu_{4} AND ν9\nu_{9} BANDS OF 1,1-DIFLUOROETHYLENE

Author Institution:The spectrum of 1,1-difluoroethylene $(CH_{2} = CF_{2})$ has been between 927 and $182 cm^{-1}$ at Doppler limited resolution using a diode laser spectrometer. Selected lines have been measured with heterodyne techniques using precisely measured $CO_{2}$ laser lines as a local oscillator. Measurement precision using this technique is about $\pm6$ MHz. The instrumentation used will be more fully described in another paper to be presented at this symposium. The region studied covers the R-branch of $\nu_{4}$, an A-type band, centered at $925.7720 cm^{-1}$ and most of the B-type band, $\nu_{9}$, at $953.8049 cm^{-1}$. About 180 lines have been measured in the $\nu_{4}$ band and 250 in the $\nu_{9}$ band. A Coriolis resonance between the $\nu_{4}$ and $\nu_{9}$ levels is possible: this resonance, however, appears to be quite weak, and the data can be fit to within measurement error using a Watson Hamiltonian with effective constants. The diode laser data were combined with microwave data from several sources to obtain an improved set of ground state constants an well as upper state constants for both bands. These constants were then used to assign 15 very precisely measured submillimeter laser transitions reported in the literature which orginate either in energy levels of $\nu_{4}$ of $\nu_{9}$. Once definitely assigned, the submillimeter data were included in the fitting, and a refined set of molecular constants obtained. Details of the band assignment, and the molecular constants obtained will be presented

WIDE-BAND TUNABLE DIODE LASER HETERODYNE MEASUREMENTS

$^{1}$ J. P. Sattler, T. L. Worchesky, K. J. Ritter, and W. J. Lafferty, Opt. Lett. 5, 21 (1980)Author Institution:A technique for rapid, accurate, and copious diode laser heterodyne measurements of infrared absorption frequencies will be discussed in $detail.^{1}$ By use of a wideband (3 dB width, 1.2 GHz) HgCdTe photomixer and a $CO_{2}$ laser local oscillator, absorptions lying within 9 GHz of a $CO_{2}$ emission line may be measured with care to within 6 MHz. The data from accurate infrared heterodyne measurements of 1,1-difluoroethylene, when supplemented with existing microwave data on the ground state, permit the calculation of submilimeter wave laser emission frequencies to within a few megahertz. Similar measurements on carbonyl sulfide increase its utility as a secondary frequency standard