Laser Stark Research Articles

Characterization of the lowest-lying Π bending state of Ar–HCl by far infrared laser–Stark spectroscopy and molecular beam electric resonance

Far infrared laser–Stark spectroscopy is used to populate an excited vibrational state in the van der Waals molecule, ArHCl, in a molecular beam. Microwave–far infrared double resonance allows the identification of this state as the first excited bending state of Π symmetry. Subsequent radio frequency electric resonance of the vibrationally excited molecule combined with far infrared–radio frequency two photon experiments gives the following spectroscopic constants: ν0−B′=33.9248(7) (cm−1), B′=1695.(20) (MHz), μ=0.265(3) (D), eqQaa=12.(7) (MHz), eqQbb−eqQcc=−73.927(23) (MHz), q1=−49.583(2) (MHz). These constants are compared with theoretical predictions obtained using previously suggested potential energy surfaces and are related to the presence of other nearby vibrational states.

Tunable diode laser Stark modulation spectroscopy for rotational assignment of the HNO 3 7.5 μm band

The technique of Stark modulation spectroscopy for unravelling and assigning rotationally resolved dense molecular spectra has been employed using a tunable diode laser (TDL) source. Doppler-limited absorption and Stark modulation spectra of the HNO 3 7.5 μm band near the 1326 cm −1 band origin are presented, with preliminary values of the excited-state rovibrational constants derived from both TDL and Bomem FTIR spectra.

A new method for electric field calibration in CO 2 laser stark spectroscopy using infrared-infrared double resonance signals of PH 3

The infrared-infrared double resonance signals observed in the Stark spectrum of PH 3 for the 10.6 μm CO 2 P(18) laser line were accurately measured. Their resonant electric fields, 2965.556±0.03 and 2972.408±0.03 V/mm, as calibrated against the LMDR signal of OCS, may be used as excellent standards for the electric field calibration in CO 2 laser Stark spectroscopy.

Rabi oscillations and rapid-passage effects in the molecular-beamCO2-laser Stark spectroscopy ofCH3F

Sub-Doppler molecular-beam laser Stark spectroscopy has been employed to produce high-contrast Rabi oscillations in the ${\ensuremath{\nu}}_{3}$ band of ${\mathrm{CH}}_{3}$F. By varying the intensity of the cw ${\mathrm{CO}}_{2}$ laser, up to five complete oscillations were observed before the phenomenon was washed out by rapid-passage effects and damping mechanisms. Besides being useful in clarifying key features of coherent ir molecular-beam spectroscopy, the observation of Rabi oscillations provides one of the most accurate means of directly measuring transition dipole moments. Analysis of the present data on three rovibrational transitions, Q(1,1) -1\ensuremath{\leftarrow}0, P(1,0) 0\ensuremath{\leftarrow}0, and R(1,1) 0\ensuremath{\leftarrow}1, has yielded a rotationless transition dipole moment of 0.21\ifmmode\pm\else\textpm\fi{}0.01 D for the ${\ensuremath{\nu}}_{3}$=1\ensuremath{\leftarrow}0 vibration. This result is in agreement with values estimated from both band-intensity and absorption-coefficient data in the literature.

Lamb-dip laser Stark spectroscopy of propyne: Analysis of the ν5 band

Laser Stark spectra for the ν5 parallel band of CH3C2H were measured by using a 13CO2 laser. Sixty resonances were assigned to transitions with a lower state, K ≤ 5. These transitions were combined with previous 12CO2-laser Stark data and zero-field lines. Effective vibration–rotation parameters and the dipole moments of the lower and upper levels were determined with high accuracy.

Hyperfine interactions in molecules through laser spectroscopy

The infrared and millimeter wave spectroscopy, laser Stark spectroscopy, and beam maser spectroscopy of CH3CN and its isotopic species will be discussed. The beam maser spectroscopy and hyperfine structure of molecules like NCCCD, ClCCD and CH3CCH are reviewed. The laser magnetic resonance and hyperfine structure in CF, CH and CH2 free radicals will be discussed. The Lamb dip spectroscopy and laser-induced fluorescence in I2 involving theB 3Π(0 u + ) state are reviewed with special reference to its hyperfine structure. The splitting of the rotational levels of N 2 + in itsX 2Σ g + andB 2Σ u + states due to hyperfine interactions (along with the hyperfine structure) in laser-induced fluorescence in theB−X transition is discussed. Recent results obtained in the laser photo-acoustic spectrum of ICl in the transitionX 1Σ+ −A 3Π1 will be presented and the possibility of the use of this technique in studying the hyperfine structure will be discussed.

Laser Stark spectroscopy of the coriolis coupled ν2 and ν5 bands of CD 3Cl

About 940 Stark resonances for CD 3 35Cl and 610 resonances for CD 3 37Cl have been measured by using a CO 2 laser with the 9- and 10-μm regions. They were assigned to 59 rovibrational transitions of ν 2 ( J′ ≤ 37, K ≤ 14) and 200 of ν 5 ( J′ ≤ 47, −14 ≤ k′ l′ ≤ +10) for 35Cl, and 31 of ν 2 ( J′ ≤ 12, K ≤ 10) and 175 of ν 5 ( J′ ≤ 46, −14 ≤ k′ l′ ≤ +9) for 37Cl. These data, combined with the microwave and FIR data in the ν 2 and ν 5 states, were analyzed by taking account of the Coriolis interaction between ν 2 and ν 5, and the (2, 2) and (2, −1) interactions in ν 5. Several Δ K = +2 transitions of the ν 5 band were observed in the Stark spectra, and the ground state constants, A 0 and D K0 , were determined precisely for both 35Cl and 37Cl species. Also, the vibrationally induced dipole moments were obtained. The molecular constants and the zero-field transition frequencies of the ν 2 and ν 5 bands were determined.

Intracavity CO_2 laser Stark spectrometer with almost-free propagation

A high performance Stark cell has been made of which the essential features are stainless steel plates, 2-mm spacing, electric fields up to 100 kV/cm, field uniformity better than 5 x 10(-5). This Stark cell has been placed at a waist created inside a CO2 laser cavity, so that the beam propagates almost freely inside the cell. Thus we get the high sensitivity of intracavity spectroscopy but we preserve the quality and the stability of extracavity spectroscopy.

Laser—Stark saturation behaviour of K = 0 levels of fluoromethane in a molecular beam

Experimental data are presented concerning the saturation using molecular beam laser—Stark spectroscopy of infrared transitions of fluoromethane involving states with ± M J degeneracy. It is shown that degenerate M x,y states more appropriately describe the results, and that a coherence is maintained between these states such that only one of them is populated by the IR transition.

Laser Stark spectroscopy

Abstract This paper discusses the development of laser Stark spectroscopy (or laser electric resonance spectroscopy) in which transitions between molecular energy levels are tuned into resonance with fixed frequency molecular gas lasers. Emphasis is laid on the fundamentals of the method, and its extensions to sub-Doppler resolution, including optical-optical double resonance and level crossing. Examples of the use of these methods are chosen from three main areas; the study of the vibrational dependence of molecular dipole moments, the elucidation of the effects of collisional energy transfer, and the detection of the spectra of semi-stable molecules.

Observation of an accidental infrared-infrared double resonance and two-photon absorption in PH 3 using a CO 2 laser

Three extra Doppler-free lines were observed in the laser Stark spectrum of phoshine, ν 2 qP(5,3), using the 1OP(18) CO 2 laser line. They were identified as the infrared-infrared double resonance and the two-photon transitions caused by the accidental overlapping of ν 2 qP(5,3) and 2ν 2-ν 2 qP(4,3).

Infrared-microwave two-photon spectroscopy of the ν4 and ν6 bands of D 2CO

Transitions in the ν 4 and ν 6 bands of D 2CO have been recorded by means of an infrared-microwave two-photon spectometer. The two-photon frequencies have been combined with frequencies obtained by infrared laser Stark and microwave spectroscopy to obtain rotational and centrifugal distortion constants for the ground, ν 4, and ν 6 states as well as vibrational frequencies and the Coriolis coupling constant for the two excited states. Expressions are reported for the linestrengths of two-photon transitions for an asymmetric rotor for the cases of parallel and perpendicular orientation of the planes of polarization of the infrared and microwave radiation.

CO2 and CO laser microwave double resonance spectroscopy of OCS: Precise measurement of dipole moment and polarizability anisotropy

Laser–microwave double resonance (LMDR) with high electric field was applied to the OCS molecule. Stark Lamb-dip spectra due to the infrared transitions of the 2ν2(0200–0000, 9.6 μm), 2ν1 (2000–0000, 5.8 μm), and ν1+2ν2 (1200–0000, 5.3 μm) bands were observed with the CO2 and CO lasers. The spectra due to the corresponding hot bands; 0310–0110, 0400–0200, 1200–1000, 1310–1110; 2110–0110, 3000–1000; 1400–0200, 1420–0220, 1510–0310, 2200–1000; and a few bands of OC34S and O13CS were also identified. Associated with these infrared transitions, more than 90 LMDR signals were detected and assigned to rotational transitions in the 11 vibrational states 0000, 1000, 2000, 0110, 0200, 0220, 0310, 0400, 1200, 1420, and 2200 of the normal species, and in the two vibrational states 0000 and 0200 of both OC34S and O13CS. Dipole moments were determined with accuracies (2.5σ) better than 2×10−5 D for all these vibrational states. Polarizability anisotropies were also obtained for some states. The data for the ground ν1 and ν2 vibrational states are, with the 2.5σ uncertainties in parentheses.From the Stark Lamb-dip spectra the origins of various vibrational bands were determined, among which those for the 0200–0000 and 0310–0110 bands are 31 389 530.4(25) and 31 566 477.57(67) MHz, respectively. The dipole moments and band origins obtained in the present study agree well with the available accurate values from molecular beam electric resonance and heterodyne measurement, respectively. A procedure for the calibration of electric field in laser Stark and double resonance spectroscopy, in which the dipole moment of OCS is used as the standard, is described.

Laser stark spectroscopy of the ν4 + ν8 − ν8 band of CH 3C 15N: Fermi resonances with 4 ν84, 4 ν82, and ( ν7 + ν8) 2

Laser Stark spectra for the ν 4 + ν 8 − ν 8 parallel band of CH 3C 15N were measured by using CO 2 and N 2O lasers in the 10-μm region. About 300 resonances have been assigned to 102 rovibrational transitions with J′ <- 16 and −9 ≤ kl ≤ +9. Anomalies observed around kl = −6 and +8 were proved to be due to the Fermi interactions with 4 ν 8 2 and 4 ν 8 4, respectively. Another Fermi interaction with ( ν 7 + ν 8) 2 was necessary to account for the anomaly around kl = −6. Observed data were analyzed by the method of least squares, and precise molecular constants have been obtained.

Laser Stark spectroscopy of the ν4 band of CH 3C 15N: Fermi resonance with 3 ν83

Laser Stark spectra for the ν 4 band of CH 3C 15N have been measured by using CO 2 and N 2O lasers. Almost 650 resonances have been assigned to about 140 ro-vibrational transitions with J′ ≤ 34 and K ≤ 11. An anomaly of the rotational structure around K = 7 has been proved to be due to a Fermi interaction by analyzing each K subband separately. Observed data have been fitted to a model which includes ν 4-3 ν 8 3 Fermi coupling by the method of least squares. The standard deviation of observed from calculated frequencies is 4.6 MHz. Molecular constants derived are also listed.

ChemInform Abstract: CARBON DIOXIDE LASER STARK SPECTROSCOPY OF THE CORIOLIS‐COUPLED ν2 AND ν5 BANDS OF BROMOMETHANE‐D3

Chemischer InformationsdienstVolume 14, Issue 39 Physical Organic Chemistry ChemInform Abstract: CARBON DIOXIDE LASER STARK SPECTROSCOPY OF THE CORIOLIS-COUPLED ν2 AND ν5 BANDS OF BROMOMETHANE-D3 K. HARADA, K. HARADASearch for more papers by this authorK. TANAKA, K. TANAKASearch for more papers by this authorT. TANAKA, T. TANAKASearch for more papers by this author K. HARADA, K. HARADASearch for more papers by this authorK. TANAKA, K. TANAKASearch for more papers by this authorT. TANAKA, T. TANAKASearch for more papers by this author First published: September 27, 1983 https://doi.org/10.1002/chin.198339047AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume14, Issue39September 27, 1983 RelatedInformation

Laser Stark spectroscopy of silyl fluoride in the 10-μm region: Analysis of the ν2 and ν5 bands

The v 2 = 1 and v 5 = 1 states of silyl fluoride are strongly mixed by Coriolis coupling. About 1100 Stark tuned resonances were measured in these bands using 12CO 2 and 13CO 2 lasers. These data were combined with 13 new millimeterwave measurements and 900 Fourier transform infrared measurements in a suitable model. Apart from the main Coriolis coupling ζ 25, it was necessary to include estimates of two further Coriolis terms to obtain a satisfactory interpretation of the data. Many vibration-rotation parameters and the dipole moments are determined.

Laser Stark spectroscopy of carbon dioxide in a molecular beam

Laser Stark spectroscopy has been performed for CO 2 molecules in a bolometrically detected supersonic beam, using a tunable infrared F-center laser to excite rovibrational transitions in the 3715-cm −1 “ ν 1 + ν 3” band of 12C 16O 2. The very weak Stark effect of CO 2 is amply resolved by realizing an effective spectroscopic linewidth of 2 MHz and by using uniform electric field strengths in excess of 200 kV cm −1. Stark spectra for the R(0) and P(2) transitions enable evaluation of the isotropic part ( α n ) and anisotropy (Δ α n ) of the static molecular polarizability in both excited ( n = v) and ground ( n = 0) vibrational states. Direct observables are Δα v Δα 0 = 1.021(8) ; (α v - α 0) Δα v = 0.012(6) ; Δα v = 2.65(18) A ̊ 3 , the last result being 12% greater than predicted. The results test the relative magnitudes of electronic and vibrational contributions to the static polarizability and indicate the way in which the polarizability tensor varies from one vibrational state to another.

Determination of the dipole moment of nitrosyl fluoride in the (001) and (101) states by combination of microwave and laser stark data.

The combination of microwave measurements of the Stark effect in the (001) excited vibrational state with fourteen laser Stark transitions of the hot band (101) ← (001), previously reported in the literature, yielded the values of the dipole moment of ONF both in the (001) and (101) states.

CO 2 laser Stark spectroscopy of the Coriolis-coupled ν2 and ν5 bands of CD 3Br

The ν 2 (CD 3 symmetrical deformation) and ν 5 (CD 3 degenerate deformation) fundamental bands of CD 3Br were studied by 9.4- and 10.4-μm CO 2 laser Stark spectroscopy. Stark resonances originating from 28 and 53 rovibrational transitions of the ν 2 and ν 5 bands, respectively, were assigned for each of the isotopic species, CD 3 79Br and CD 3 81Br. These two bands were simultaneously analyzed with explicit inclusion of the ν 2- ν 5 Coriolis interaction, yielding precise molecular constants in the ν 2 and ν 5 excited states as well as the Coriolis coupling constant. The molecular constants obtained are consistent between the two isotopic species and are in good agreement with the results of high-resolution infrared studies. The band origins and dipole moments are CD 3 79Br CD 3 81Br ν 2 991.396 82 (18) 991.388 46 (17) cm −1 ν 5 1055.469 00 (12) 1055.466 32 (12) cm −1 μ 0 1.830 42 (52) 1.829 84 (47) D μ 2 1.829 93 (48) 1.829 57 (46) D μ 5 1.832 23 (60) 1.831 19 (56) D where the figures in parentheses are three times the standard deviations in the least-squares fit.