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1.
Wen-Bin Yan R.F. Curl Anthony J. Merer Patrick G. Carrick 《Journal of Molecular Spectroscopy》1985,112(2):436-446
The magnetic rotation observation of the C2b3Σg? ← a3Πu Ballik-Ramsay system using a color center laser is reported. This is the first detection of this system in absorption. Three bands, 0 ← 1, 1 ← 2, and 2 ← 3, were identified in the spectral range 3650–4030 cm?1. The last two bands were observed for the first time. In magnetic rotation many satellite lines (ΔN ≠ ΔJ) which would be very weak in normal absorption have been observed with intensity comparable to the main branch lines. This permits a slight improvement in the accuracy of some of the fine structure constants. A variety of lineshapes are observed for the various branches by magnetic rotation. Because the b3Σg? fine structure is small, giving a partial overlap, the peak frequency of a magnetic rotation signal usually does not correspond to the center frequency of the normal absorption signal of that transition. A computer program has been written to predict magnetic rotation lineshapes and obtain the peak frequency displacements. Various observed and calculated lineshapes are displayed and compared. 相似文献
2.
M.?Horstjann Y.A.?Bakhirkin A.A.?Kosterev R.F.?Curl F.K.?TittelEmail author C.M.?Wong C.J.?Hill R.Q.?Yang 《Applied physics. B, Lasers and optics》2004,79(7):799-803
A novel continuous-wave mid-infrared distributed feedback interband cascade laser was utilized to detect and quantify formaldehyde (H2CO) using quartz-enhanced photoacoustic spectroscopy. The laser was operated at liquid-nitrogen temperatures and provided single-mode output powers of up to 12 mW at 3.53 m (2832.5 cm-1). The noise equivalent (1) detection sensitivity of the sensor was measured to be 2.2×10-8 cm-1W(Hz)-1/2 for H2CO in ambient air, which corresponds to a detection limit of 0.6 parts in 106 by volume (ppmv) for a 10 s sensor time constant and 3.4 mW laser power delivered to the sensor module. PACS 42.62.Fi; 72.50.+b 相似文献
3.
Mariza Pires de Melo† Tania Cristina Pithon Curi Rui Curl Paolo Di Mascio Giuseppe Cilento 《Photochemistry and photobiology》1997,65(2):338-341
Peroxidase activity in neutrophils is higher than in thioglycollate macrophages, while in lymphocytes this enzyme activity is very low. Indole-3-acetic acid is oxidized by peroxidase and the role of this enzyme in the cytotoxic effect of the compound was evaluated by measuring oxygen consumption, light emission and cell death in neutrophils, macrophages and lymphocytes. The increase in light emission, oxygen consumption and rate of cell death in cells cultured in the presence of indole-3-acetic acid presented a direct correlation with the peroxidase activity of the cells as follows: neutrophils > thioglycollate macrophages > resident macrophages > lymphocytes. Indeed, in lymphocytes that possess very low peroxidase activity, indole-3-acetic acid did not result in an increase in light emission or oxygen consumption and it was not cytotoxic. 相似文献
4.
5.
Charles D. LeCroix R.F. Curl Peter M. McKinney Rollie J. Myers 《Journal of Molecular Spectroscopy》1974,53(2):250-272
The microwave spectra of silyl methyl ether, SiH3OCH3, and its isotopic modifications, SiH3OCD3, SiD3OCH3, and SiD3OCD3, have been observed and assigned. Large splittings arising from the internal rotation of the methyl top and somewhat smaller splittings arising from the internal rotation of the silyl top are observed. The “effective barrier” to internal rotation of the methyl top is approximately 550 cal/mole. The effective barrier to internal rotation of the silyl top is approximately 1100 cal/mole. The internal rotation of the two tops is strongly coupled, but no values for the potential coupling constants have been obtained. The dipole moment has been determined to be 1.15 ± 0.02 D (|μa| = 0.647 ± 0.01 and |μb| = 0.95 ± 0.02 D) from measurements of the Stark effect. 相似文献
6.
The photoluminescence spectrum of PH2 excited by a cw dye laser shows resolved 13P hyperfine structure for the 000 level even in the presence of Doppler broadening. The observed splittings give a Femi contact constant for the (0,0,0) Ã2A1 state of PH2 of 1.8 ± 0.1 GHz. 相似文献
7.
K. P. Petrov S. Waltman U. Simon R. F. Curl F. K. Tittel E. J. Dlugokencky L. Hollberg 《Applied physics. B, Lasers and optics》1995,61(6):553-558
Spectroscopic detection of the methane in natural air using an 800 nm diode laser and a diode-pumped 1064 nm Nd:YAG laser to produce tunable light near 3.2 µm is reported. The lasers were pump sources for ring-cavity-enhanced tunable difference-frequency mixing in AgGaS2. IR frequency tuning between 3076 and 3183 cm–1 was performed by crystal rotation and tuning of the extended-cavity diode laser. Feedback stabilization of the IR power reduced intensity noise below the detector noise level. Direct absorption and wavelength-modulation (2f) spectroscopy of the methane in natural air at 10.7 kPa (80 torr) were performed in a 1 m single-pass cell with 1 µW probe power. Methane has also been detected using a 3.2 µm confocal build-up cavity in conjunction with an intracavity absorption cell. The best methane detection limit observed was 12 ppb m (Hz.)–1/2. 相似文献
8.
D. Richter D.G. Lancaster R.F. Curl W. Neu F.K. Tittel 《Applied physics. B, Lasers and optics》1998,67(3):347-350
3 (PPLN) crystal pumped by two single-frequency diode lasers. A maximum DFG power of 1.6 μW at 3.6 μm was generated with a pump
power of 61.4 mW at 832 nm and a signal power of 41.5 mW at 1083 nm incident on a 19-mm-long PPLN crystal, which corresponds
to a conversion efficiency of 335 μW W-2 cm-1.
Received: 16 June 1998 相似文献
9.
2 O), carbon dioxide (CO2), and sulfur dioxide (SO2). Real-time detection of CO, N2O, and CO2 was performed in open air over a path length of 5 to 18 m. The feasibility of DFG spectroscopic measurement of the 13C/12C and 18O/17O/16O isotopic ratios in atmospheric carbon dioxide was also investigated. We report what to our knowledge is the first simultaneous
spectroscopic measurement of all three isotopes of oxygen in ambient CO2.
Received: 14 August 1997/Revised version: 3 November 1997 相似文献
10.
Real-time measurements of trace gases using a compact difference-frequency-based sensor operating at 3.5 μm 总被引:17,自引:0,他引:17
D.G. Lancaster D. Richter R.F. Curl F.K. Tittel 《Applied physics. B, Lasers and optics》1998,66(3):339-345
3 for on-line absorption measurements of H2CO, CH4, and H2O near 3.5 μm is reported. Formaldehyde levels of 30 ppb, corresponding to absorptions of 2×10-4 have been measured using absorption spectroscopy. In this paper we report specifically the performance of this sensor as
part of the 1997 Lunar–Mars Life Support Test program at the NASA Johnson Space Center.
Received: 1 April 1998 相似文献