Showing papers by "Richard J. Saykally published in 1988"
TL;DR: The first high resolution spectra of a rare gas-H2O cluster have been observed using a tunable far infrared laser to probe the vibration-rotation-tunneling levels of Ar 2O formed in a continuous planar supersonic jet.
Abstract: The first high resolution spectra of a rare gas–H2O cluster have been observed using a tunable far infrared laser to probe the vibration–rotation–tunneling levels of Ar–H2O formed in a continuous planar supersonic jet. The high sensitivity of this spectrometer facilitated extensive measurements of two perpendicular subbands which are assigned to transitions from the ground state to the upper component of a hydrogen exchange tunneling doublet (c-type) at 21 cm^−1, and to vb1 =1+ (b-type) at 25 cm^−1, the lower tunneling component of a bending vibration which is perpendicular to the tunneling coordinate. The tunneling splitting is shown to be in the range 2.5–7 cm^−1 and the lower tunneling component of the excited bending vibration lies between 39 and 43 cm^−1 above the ground state of the complex. The experimentally determined center-of-mass separation (Rc.m. =3.75 A) and harmonic stretching force constant (ks =0.0134 mdyn/A) are compared to those of related first and second row hydrides. The large amplitude motions occurring within this complex make it difficult to establish its structure.
101 citations
TL;DR: A tunable far infrared laser system has been used to measure the vibration-rotation spectrum of the lowest bending state of ArHCl near 24 cm−1 in a cw planar jet operating with a terminal jet temperature near 3 K.
Abstract: A tunable far infrared laser system has been used to measure the vibration–rotation spectrum of the lowest Σ bending state of ArHCl near 24 cm−1 in a cw planar jet operating with a terminal jet temperature near 3 K. Over 60 transitions have been observed for both 35Cl and 37Cl isotopes with resolution of the quadrupole hyperfine structure. An improved set of molecular parameters was determined, including B, D, H, and eqQ for both upper and lower states. Very narrow linewidths (approximately 300 kHz) resulting in high resolution and sensitivity make this technique a powerful new method for the detailed investigation of intermolecular forces.
76 citations
TL;DR: The ground state K_a = 0(u)→1(g) b-type subband of the rotation-tunneling spectrum of the symmetric hydrogen chloride dimers has been recorded near 26.3 cm^(−1) with sub-Doppler resolution in a continuous two-dimensional supersonic jet with a tunable far-infrared laser spectrometer as mentioned in this paper.
Abstract: The ground state K_a =0(u)→1(g) b‐type subband of the rotation–tunneling spectrum of the symmetric ^(35)Cl–^(35)Cl,^(37)Cl–^(37)Cl, and the mixed ^(35)Cl–^(37)Cl hydrogen chloride dimers have been recorded near 26.3 cm^(−1) with sub‐Doppler resolution in a continuous two‐dimensional supersonic jet with a tunable far‐infrared laser spectrometer. Quadrupole hyperfine structure from the chlorine nuclei has been resolved. From the fitted rotational constants a (H^(35)Cl)_2 center‐of‐mass separation of 3.81 A is derived for the K_a =1(g) levels, while the nuclear quadrupole coupling constants yield a vibrationally averaged angular structure for both tunneling states of approximately 20–25 deg for the hydrogen bonded proton and at least 70–75 deg for the external proton. This nearly orthogonal structure agrees well with that predicted by ab initio theoretical calculations, but the observed splittings and intensity alterations of the lines indicate that the chlorine nuclei are made equivalent by a large amplitude tunneling motion of the HCl monomers. A similar geared internal rotation tunneling motion has been found for the HF dimer, but here the effect is much greater. The ground state tunneling splittings are estimated to lie between 15–18 cm^(−1), and the selection rules observed indicate that the trans tunneling path dominates the large amplitude motion, as expected, provided the dimer remains planar. From the observed hyperfine constants, we judge the dimer and its associated tunneling motion to be planar to within 10°.
68 citations
TL;DR: The development of new techniques for infrared laser spectroscopy of molecular ions has resulted in an explosion of high-quality data for important charged molecules as discussed by the authors, which will have an important impact on chemistry, biology, and astrophysics.
Abstract: The development of new techniques for infrared laser spectroscopy of molecular ions has resulted in an explosion of high-quality data for important charged molecules. Velocity modulation laser spectroscopy, which exploits the motions of charged particles in electrical plasmas to eliminate interference from neutral absorbers, is rapidly producing a large body of new results for both positive and negative molecular ions. This information will have an important impact on chemistry, biology, and astrophysics. 26 references, 2 figures.
55 citations
TL;DR: In this paper, the authors measured 43 transitions in the pure rotational and fundamental vibrational spectra of 18 OH +, together with all ground state transitions and combination differences of OH + and 16 OH + available from the literature, have been fit to an explicity internuclear distance dependent rovibrational Hamiltonian.
28 citations
TL;DR: In this paper, the authors measured 43 transitions centered at 1972 cm−1 in the (011) −(001) bending hot band of the azide ion (N−3) using diode laser velocity modulation spectroscopy of an NH3/N2O discharge.
Abstract: We have measured 43 transitions centered at 1972 cm−1 in the (011)–(001) bending hot band of the azide ion (N−3) using diode laser velocity modulation spectroscopy of an NH3/N2O discharge The data, ranging from P(32) to R(40), were fit to a standard l‐type doubling Hamiltonian through quartic terms The l splittings in the spectrum were unusually large compared with similar molecules Intensity measurements indicate that the vibrational and rotational degrees of freedom are equilibrated, unlike the case for isoelectronic NCO− Additional lines of the ν3 fundamental have also been measured, which further refine the values of the ground state parameters
25 citations
TL;DR: In this article, the first experimental determination of the dipole moment of a molecular ion from the rotational Zeeman effect is presented, along with an assessment of the ultimate accuracy of the technique.
Abstract: The details of the first experimental determination of the dipole moment of a molecular ion from the rotational Zeeman effect are presented, along with an assessment of the ultimate accuracy of the technique.
21 citations
TL;DR: In this paper, a complete analysis of the FIR laser Stark/microwave double resonance spectrum of the bending vibration of ArHCl is given, and the authors provide strong support for the existence of a secondary minimum in the intermolecular potential surface at the linear ArClH geometry.
Abstract: A complete analysis of the FIR laser Stark/microwave double resonance spectrum of the Σ bending vibration of ArHCl is given. Hyperfine-resolved spectra of the R(0), R(1), R(2), and P(1) transitions were measured near 25 cm-1 for both chlorine isotopes. Accurate values for the band origins, rotational constants, dipole moments, and quadrupole hyperfine constants were obtained. Comparison with Hutson's close-coupling calculations provide very strong support for the existence of a secondary minimum in the intermolecular potential surface at the linear ArClH geometry.
19 citations
TL;DR: In this paper, a new method based on velocity modulation laser spectroscopy is described for the nonperturbative measurement of the axial electric fields in glow discharges in the A 2 Π u ←X 2 Σ g + (4, 0) band of N 2 + has been used as a probe of a He/N 2 discharge.
15 citations
TL;DR: The velocity-modulation technique has been used with colour-centre lasers and diode lasers throughout the vibrational infrared region to measure high-resolution vibration-rotation spectra of fundamental anions.
Abstract: The velocity-modulation technique has been used with colour-centre lasers and diode lasers throughout the vibrational infrared region to measure high-resolution vibration-rotation spectra of fundamental anions.
8 citations
TL;DR: The development of new techniques for infrared laser spectroscopy of molecular ions has resulted in an explosion of high-quality data for important charged molecules as mentioned in this paper, which will have an important impact on chemistry, biology, and astrophysics.
Abstract: The development of new techniques for infrared laser spectroscopy of molecular ions has resulted in an explosion of high-quality data for important charged molecules. Velocity modulation laser spectroscopy, which exploits the motions of charged particles in electrical plasmas to eliminate interference from neutral absorbers, is rapidly producing a large body of new results for both positive and negative molecular ions. This information will have an important impact on chemistry, biology, and astrophysics. 26 references, 2 figures.
TL;DR: In this paper, the Stark coefficients in the lambda doubling transition of a 3 ε CO were reanalyzed and the dipole moment in the a ε3 ε+ state and the transition moment between ε and ε −0.79 and +0.64 D, respectively.
Abstract: The highly precise measurements of Stark coefficients in the lambda doubling transitions of a 3Π CO obtained in previously published molecular beam electric resonance experiments have been reanalyzed. Certain perturbations between vibrational levels of the a 3Π and a’ 3Σ+ states that were neglected in the earlier treatment have been found to be important. An apparent error, by a factor of in the Stark matrix elements that were used in prior work, has also been corrected. The previously reported experimental determination of the dipole moment function of a 3Π CO is shown to be invalid. Thus, the relatively flat appearance of the dipole moment function found in previous ab initio studies may indeed be correct. The dipole moment in the a’ 3Σ+ state and the transition moment between the a 3Π and a’ 3Σ+ states are substantially revised to −0.79 and +0.64 D, respectively.
01 Jan 1988
TL;DR: In this article, the authors proposed a method to detect the presence of asteroids in the Earth's magnetic field using a geodesic model of the Earth and its magnetic field, and applied it to the Earth sciences.
Abstract: Author Institution: Department of Chemistry, University of California; Division of Geological and Planetary Science, California Institute of Technology