Millimeter-Wave Spectroscopy of Sulfur Dichloride

The rotational spectra of (32)S(35)Cl(2), (32)S(35)Cl(37)Cl, (32)S(37)Cl(2), and (34)S(35)Cl(2) in their ground vibrational states, as well as those of (32)S(35)Cl(2) and (32)S(35)Cl(37)Cl in their nu(2) and 2nu(2) excited states, have been studied in selected frequency regions between 100 and 370 GHz. Transitions involving a large range of quantum numbers have been observed, so that precise rotational and quartic centrifugal distortion constants could be determined for each of the spectra investigated. The complete set of sextic distortion constants was also obtained for the most abundant isotopomer in its ground vibrational state. The newly determined rotational constants of (34)S(35)Cl(2) and (32)S(37)Cl(2) allowed us to calculate the complete r(s) structure of sulfur dichloride using both single- and double-isotopic substitution methods. The quadratic force field has been refined using a larger set of quartic distortion constants and inertial defects. Copyright 2000 Academic Press.     

Infrared Diode Laser Spectrum of the nu(1) Fundamental Band of ClBO

The nu(1) band of ClBO has been recorded using infrared diode laser spectroscopy. The molecule was produced by reacting oxygen atoms, produced in a microwave discharge containing an O(2)/He mixture, with BCl(3). Thirty-three lines of the (35)Cl(11)B(16)O isotopomer and 32 lines due to the (37)Cl(11)B(16)O isotopomer have been assigned. By fixing the ground state constants to those previously obtained by microwave spectroscopy, a least-squares fit (rms = 0.0008) gave the following upper state constants; (35)Cl(11)B(16)O: nu(0) = 1972.18024(21) cm(-1), B(1) = 0.1725055(12) cm(-1); (37)Cl(11)B(16)O: nu(0) = 1971.82846(24) cm(-1), B(1) = 0.1688402(13) cm(-1). The rotational constants of all the fundamental bands of ClBO have been used to calculate an r(e) structure yielding r(e(B-Cl)) = 167.668(26) pm and r(e(B-O)) = 121.308(26) pm. Copyright 2000 Academic Press.     

Diode-Laser Jet Spectra and Analysis of the nu(1) and nu(4) Fundamentals of CCl(3)F

High-resolution infrared spectra have been measured for mixtures of CCl(3)F in Ne, expanded in a supersonic planar jet. We present the first analysis for the nu(4) fundamental and a complete analysis for the nu(1) band. Accurate spectroscopic constants have been obtained for both the nu(1) fundamental of the most abundant isotopic species, C(35)Cl(3)F, C(35)Cl(2)(37)ClF, and C(35)Cl(37)Cl(2)F. With respect to an earlier work [M. Snels, A. Beil, H. Hollenstein, M. Quack, U. Schmidt, and F. D'Amato, J. Chem. Phys. 103, 8846-8853 (1995)], the observation of Q branches of the three most abundant isotopomers allowed for an unambiguous determination of the nu(1) band origins. The nu(4) fundamental has not been the subject of a high-resolution analysis up to now. The observation of high-resolution spectra of the central part of the band permitted the determination of band origin, rotational constants, and Coriolis constant for the symmetric-top species, C(35)Cl(3)F. Copyright 2001 Academic Press.     

Diode-Laser Spectroscopy of the nu(19a) Band of Chlorobenzene in a Supersonic Jet

The diode-laser absorption spectrum of the nu(19a) band of the chlorobenzene molecule cooled in a supersonic jet is presented and transitions from low J, K(a), and K(c) values (0-14) are reported. The C(6)H(5)(35)Cl band center has been found at nu(0) = 1483.894 cm(-1) and rotational constants for the upper state have been determined from a least-squares fitting to experimental data. The band center for the C(6)H(5)(37)Cl isotope has also been obtained. Copyright 2000 Academic Press.     

High-Resolution Infrared, Microwave, and Submillimeter-Wave Study of FClO(2) in the nu(2), nu(3), nu(4), and nu(6) Excited States

A high-resolution analysis of the {nu(2), nu(3)} and {nu(4), nu(6)} bands of the two isotopomers of chloryl fluoride F(35)ClO(2) and F(37)ClO(2) has been carried out for the first time using simultaneously infrared spectra recorded around 16&mgr;m and 26&mgr;m with a resolution of ca. 0.003 cm(-1) and microwave and submillimeter-wave transitions occurring within the vibrational states 2(1), 3(1), 4(1), and 6(1). Taking into account the Coriolis resonances which link the rotational levels of the {2(1), 3(1)} and the {4(1), 6(1)} interacting states, it was possible to reproduce very satisfactorily the observed transitions and to determine accurate vibrational energies and rotational constants for the upper states 2(1), 3(1), 4(1), and 6(1) of both the (35)Cl and (37)Cl isotopic species. Copyright 2001 Academic Press.     

High-Resolution Spectroscopy of Jet-Cooled (32)SO(2) and (34)SO(2): The ã(3)B(1)-;X(1)A(1), 2(1)(0) and 1(1)(0) Bands

Laser-induced excitation spectra of the two bands ?(3)B(1)-;X(1)A(1), 2(1)(0) and 1(1)(0) of (32)SO(2) and (34)SO(2) have been recorded in a supersonic jet at a resolution of 0.015 cm(-1). The rotational and electron-spin fine structure has been analyzed for both isotopic species. Analysis of the rotational and electron-spin fine structure yields precise values of the rotational constants A, B, and C and the spin constants alpha and beta for both (32)SO(2) and (34)SO(2) in the states ?(3)B(1) (010) and (100). No interaction between these two vibrational states with any nearby triplet state is observed for rotational levels with J 相似文献   

Microwave spectra of the Cl and Cl isotopomers of dichloromethylene: Nuclear quadrupole-, spin-rotation-, and nuclear shielding constants from the hyperfine structures of rotational lines

The rotational spectra of the isotopomers C³⁵Cl³⁷Cl and C³⁷Cl₂ of dichloromethylene in the ground vibronic state were recorded in the range 10-33 GHz using a molecular beam Fourier transform microwave spectrometer. CCl₂ was generated by flash pyrolysis using different precursors. The observed spectra were analyzed to yield rotational and centrifugal distortion constants, as well as the complete Cl nuclear quadrupole coupling tensors and the spin-rotation interaction constants from the hyperfine structure of the rotational lines. With inclusion of data from previous work on the most abundant species C³⁵Cl₂ [N. Hansen, H. Mäder, F. Temps, Phys. Chem. Chem. Phys. (3) (2001) 50-55.] a refined r₀ structure was determined. The spin-rotation interaction constants of all three isotopomers were used to derive ³⁵Cl and ³⁷Cl principal inertial axis nuclear magnetic shielding components which have not yet been determined by NMR spectroscopy.     

CH^35Cl3和CH^35Cl2^37Cl分子V=3的傅里叶变换光谱研究

采用傅里叶变换光谱技术（ＦＴＳ）记录了ＣＨ＾３５Ｃｌ３和它的同位素分子ＣＨ＾３５Ｃｌ２＾３７Ｃｌ的Ｖ＝３的高分辨光谱，由于０．０２ｍ＾－１分经不足以分辨Ｋ结构，我们将所观察到的谱线近似归属为Ｋ＝０的转动能级，归属了ＣＨ＾３５Ｃｌ３岔子４〈Ｊ〈７３，ＣＨ＾３５Ｃｌ＾３７Ｃｌ分子６〈Ｊ〈５３的转动级。最后采用最小二乘法拟合，得到了关于Ｊ的转动常数和振动带心。     

High-Resolution Infrared Study of the nu(7), nu(8), and nu(15) Bands and Millimeter-Wave Investigation of the v(8) = 1 State of CF(2)Cl-CH(3)

High-resolution (Deltavarsigma = 2.3 and 2.9 x 10(-3) cm(-1)) FTIR spectra of natural and (35)Cl monoisotopic CH(3)CF(2)Cl have been recorded at -70 degrees C in the 600-1400 cm(-1) range. The bands nu(7), nu(8), and nu(15) have been rotationally analyzed for both isotopic varieties. With the help of predictions based on nu(8) parameters, the millimeter-wave spectrum of the (35)Cl species in the v(8) = 1 state has been observed and jointly fitted with the IR data. Only a small number of local perturbations have been detected in the spectra. Altogether more than 8000 IR transitions have been fitted with an experimental precision of ca. 3 x 10(-4) cm(-1). Copyright 2000 Academic Press.     

Rotational spectra, nuclear quadrupole hyperfine tensors, and conformational structures of the mustard gas simulent 2-chloroethyl ethyl sulfide

Rotational spectra have been recorded for both the ³⁵Cl and ³⁷Cl isotopic forms of two structural conformations of 2-chloroethyl ethyl sulfide (CEES). The rotational constants of the ³⁵Cl and ³⁷Cl isotopomers were used to identify the conformational isomers. A total of 236 hyperfine transitions have been assigned for 47 rotational transitions of the ³⁵Cl isotope of a GGT conformer, and 146 hyperfine have been assigned for 37 rotational transitions of the ³⁷Cl isotopomer. For the second conformer, a total of 128 (110) hyperfine and 30 (28) rotational transitions have also been assigned to the ³⁵Cl (³⁷Cl) isotopes of a TGT conformation. The extensive hyperfine splitting data, measured to high resolution with a compact Fourier transform microwave spectrometer, were used to determine both the diagonal and off-diagonal elements of the ³⁵Cl and ³⁷Cl nuclear quadrupole coupling tensors in the inertial tensor principal axis system. The experimental rotational constant data, as well as the ³⁵Cl and ³⁷Cl nuclear quadrupole coupling tensors, were compared to the results from 27 optimized ab initio (HF/6-311++G^∗∗ and MP2/6-311++G^∗∗) model structures.     

High Resolution FTIR Spectroscopy of DCCCl: Anharmonic Resonances in the nu(1) and nu(2) Bands

High-resolution infrared spectra of the nu(1) and nu(2) bands of DCCCl were observed using Bruker IFS 120HR Fourier transform spectrometers at resolutions of 0.0044 and 0.0035 cm(-1), respectively. For the DCC(35)Cl isotopomer, the nu(1) as well as the nu(2) band was found to be heavily perturbed. Detailed analyses revealed that the nu(1) state is in resonance with the l=0 substate of the nu(3)+4nu(4) state and that the nu(2) state is in resonance with the l=0 substate of the nu(3)+4nu(5) state. The rotational constants played a key role in identifying the perturbing states. In contrast, for the DCC(37)Cl isotopomer, the rotational structures of the nu(1) and nu(2) states are almost regular but slightly perturbed by interactions with the nu(3)+4nu(4) and nu(3)+4nu(5) states, respectively. The constants of resonances as well as the molecular constants for the nu(1), nu(2), nu(3)+4nu(4) and nu(3)+4nu(5) states were determined. Copyright 2001 Academic Press.     

Rotational Spectroscopy of HBS: The Quadrupole Coupling Constant of S in Thioborine

The unstable HBS molecule has been produced in the gas phase by a high-temperature reaction between crystalline boron and hydrogen sulfide. Ground state rotational spectra have been observed in the millimeter-wave region, from 75 to 460 GHz, for the previously unobserved H¹¹B³³S and H¹⁰B³³S isotopic species. The analysis of the hyperfine structure produced by the ^10/11B and ³³S nuclear spins in the low-J rotational transitions has yielded the first evaluation of the quadrupole coupling constant of 33S in the thioborine molecule, which was 6.361(15) MHz in H¹¹B³³S and 6.329(17) MHz in H¹⁰B³³S. In addition, further measurements have been performed for the most abundant isotopomers H^10/11B^32/34S, for which improved values of rotational, centrifugal, and hyperfine structure constants have been determined.     

Molecular constants for NSCl and NSF

The complete infrared spectrum of gaseous NSCl, including the hitherto unobserved ν₃, is reported. A set of force constants for gaseous NSCl consistent with a number of pieces of independent data such as the isotopic shifts (¹⁴N³²S³⁵Cl, ¹⁵N³²S³⁵Cl, ¹⁴N³²S³⁷Cl, ¹⁵N³²S³⁷Cl, ¹⁴N³⁴S³⁵Cl and ¹⁵N³⁴S³⁵Cl), centrifugal distortion constants (¹⁴N³²S³⁵Cl), and the inertia defect (¹⁴N³²S³⁵Cl) has been computed. Also, the force field of NSF has been redetermined using the vibrational frequencies and the centrifugal distortion constants.     

Microwave spectrum of 2-chloropyridine

The microwave spectrum of 2-chloropyridine, C₅H₄NCl, has been studied in the frequency range from 26.5–40.0 GHz. The spectrum is characterized by strong parallel type transitions of a near-prolate asymmetric top. The assigned transitions have been used to evaluate the ground state rotational constants of the two chlorine isotopes. The rotational constants are (in MHz): A = 5872.52, B = 1637.83, C = 1280.48 for the ³⁵Cl isotopic species and A = 5872.16, B = 1591.76, C = 1252.17 for the ³⁷Cl isotopic species. The small inertial defect indicates the molecule is planar. In addition an excited vibrational state of C₅H₄N³⁵Cl has been observed and analyzed. The chlorine quadrupolar coupling constants were determined for the ground state and are: χ_aa = ?71.9 MHz for ³⁵Cl and χ_aa = ?54.9 MHz for ³⁷Cl. By assuming the pyridine ring structure the CCl bond length is found to be 1.72 Å.     

The pure rotational spectrum of ZnCl (XΣ): Variations in zinc halide bonding

The radical ZnCl (X²Σ⁺) has been studied using millimeter-wave direct-absorption techniques. Pure rotational spectra of ⁶⁷Zn³⁵Cl, ⁶⁶Zn³⁷Cl, ⁶⁸Zn³⁵Cl, ⁶⁴Zn³⁵Cl, ⁶⁴Zn³⁷Cl, and ⁶⁶Zn³⁵Cl were measured in the vibrational ground state and data were also recorded for the latter three in the v = 1 and v = 2 states. Every rotational transition was found to be split into a doublet due to spin-rotation interactions. For ⁶⁷Zn³⁵Cl, each doublet exhibited additional splittings arising from hyperfine coupling of the ⁶⁷Zn (I = 5/2) nucleus. Rotational, fine structure, and hyperfine constants have been determined from these data, and equilibrium parameters calculated. The equilibrium bond length of ⁶⁴Zn³⁵Cl is found to be 2.13003305(24) Å, in good agreement with recent theoretical predictions. Interpretation of hyperfine constants indicates that the 12σ orbital is ∼70% Zn(4s) in character, suggesting that the zinc chloride bond is relatively ionic.     

Microwave spectra of eight isotopic modifications of 1-chloro-1-fluoroethylene

The rotational spectra of eight isotopomers of 1-chloro-1-fluoroethylene in the 6-22 GHz region have been collected and analyzed. Each rotational transition is split into hyperfine components by the chlorine (either ³⁵Cl or ³⁷Cl) nuclear quadrupole coupling interaction and additionally, one or more smaller interactions such as the spin-rotation interaction due to the fluorine atom, hydrogen-hydrogen spin-spin coupling interactions, and in appropriately substituted species, the deuterium nuclear quadrupole hyperfine interaction. The rotational constants derived from these isotopomers allow the determination of average and Kraitchman substitution structures for 1-chloro-1-fluoroethylene, whereas the availability of the diagonal chlorine nuclear quadrupole coupling constants for all the isotopomers provides complete quadrupole coupling tensors for both ³⁵Cl and ³⁷Cl. In the course of this work, the rotational spectrum of an excited vibrational state of the normal isotopomer was observed, which ab initio calculations suggest should be assigned to ν₉=1, an in-plane bending motion at the CFCl end of the molecule.     

Pure rotational spectra of 32SF535Cl, 32SF537Cl,and 34SF535Cl up to 300 GHz

Pure rotational spectra of the three molecules ³²SF₅³⁵Cl, ³²SF₅³⁷Cl, and ³⁴SF₅³⁵Cl in their ground vibrational states have been observed up to 300 GHz (8 < J < 80). Molecular parameters have been computed with good accuracy for the three isotopic species. The “K-type” splitting characteristic of molecules belonging to the C_4v symmetry group has been clearly seen and measured.     

The microwave spectrum,harmonic force field,and structure of difluorodichloromethane

Very large numbers of rotational transitions have been accurately measured for ¹²CF₂³⁵Cl₂, ¹²CF₂³⁵Cl³⁷Cl, and ¹³CF₂³⁵Cl₂, and have been analyzed for rotational constants and quartic centrifugal distortion constants. The distortion constants have been combined with vibrational wavenumbers (both from the literature and from the present work), and with ab initio force constants also evaluated in the present work, to give an approximate harmonic force field. The rotational constants and force field have been used to evaluate ground state effective, substitution, and ground state average structures for the molecule.     

Hyperfine structure of the J=1←0 transition of HCl and HCl: improved ground state parameters

The pure rotational J=1←0 transitions of H³⁵Cl and H³⁷Cl have been observed in the millimeter-wave region using the Lamb-dip technique to resolve the hyperfine structure due to ³⁵Cl or ³⁷Cl and H. The present observations allow to provide not only very accurate hyperfine constants but also, joint together with previous data, the most accurate ground state rotational parameters known up to now. The experimental determination of the hyperfine parameters has also been supported by ab initio computations.     

The Hyperfine Structures of ScCl and ScF

The Fourier transform microwave spectra of gaseous ScF and ScCl have been measured in their (1)Sigma(+) ground electronic states. Transitions have been observed for ScF (J = 1-0) and for both Sc(35)Cl and Sc(37)Cl (J = 1-0 and J = 2-1) in the ground vibrational state, and for Sc(35)Cl (J = 1-0 and J = 2-1) in the first excited vibrational state. The nuclear quadrupole coupling constants of Sc and of both isotopes of Cl, the spin-rotation constants for all the nuclei and the nuclear spin-nuclear spin constants for both molecules, have been determined. From these hyperfine constants, the electronic structures of ScF and ScCl have been investigated and comparisons have been made to similar molecules. ScCl has been found to be highly ionic. For Sc(35)Cl, the equilibrium bond length has been reevaluated and the vibration frequency and dissociation energy have been estimated. A simple approach to account for the Sc quadrupole coupling constants has been shown to be flawed. Copyright 2000 Academic Press.