Showing papers by "Richard J. Saykally published in 1983"
302 citations
TL;DR: In this article, the spin-orbit matrix element between the singlet and triplet levels of CH2 has been used to assign the levels that perturb each other and calculate the radiative lifetimes of the lowest ortho and para levels.
Abstract: We have observed and assigned a number of far infrared laser magnetic resonance spectra of CH2 arising from rotational transitions within the lowest vibrational state of the a 1A1 electronic excited state and from transitions between such singlet levels and vibrationally excited levels of the X 3B1 electronic ground state The singlet–singlet transitions are magnetically active, and the singlet–triplet transitions have electric dipole intensity because of the spin‐orbit mixing of singlet levels with vibrationally excited levels of the triplet state By identifying four pairs of singlet and triplet levels that perturb each other we can accurately position the singlet and triplet state relative to each other and determine the single–triplet energy splitting We determine that T0(a 1A1)=3165±20 cm−1 (905±006 kcal/mol; 0392±0003 eV), and Te(a 1A1)=2994±30 cm−1 (856±009 kcal/mol; 0371±0004 eV) A new ab initio calculation of the spin‐orbit matrix element between these two states has been of assistance in assigning the levels that perturb each other and has enabled us to calculate the radiative lifetimes of the lowest ortho and para levels of the a 1A1 state to be about 18 s in each case
258 citations
TL;DR: The first high-resolution measurement of the vibration (doubly degenerate asymmetric stretch) of the hydronium ion (${\mathrm{H}}_{3}$${O}}^{+}$) is reported in this article.
Abstract: The first high-resolution measurement of the ${\ensuremath{
u}}_{3}$ vibration (doubly degenerate asymmetric stretch) of the hydronium ion (${\mathrm{H}}_{3}$${\mathrm{O}}^{+}$) is reported. An analysis of sixty transitions in the symmetric and antisymmetric inversion states yields effective band origins of 3530.165(55) and 3513.840(47) ${\mathrm{cm}}^{\ensuremath{-}1}$, respectively.
133 citations
86 citations
TL;DR: In this paper, the velocity modulated absorption spectroscopy (VMS) was used to measure the ammonium ion near 3.0 μm with a color center laser spectrometer.
Abstract: The ν3 band of the ammonium ion was measured near 3.0 μm with a color center laser spectrometer using the technique of velocity modulated absorption spectroscopy. NH4+ was produced in an ac discharge containing 0.1 Torr of nH3 and 1.5 Torr of H2. Seventy individual transitions were measured with an accuracy of 1×10−6 and assigned to q0, P+, and R− branches of a tetrahedral molecule. The constants derived in a preliminary analysis are: νeff0=3342.540 2(97) cm−1, B0+B1−2B1χ3=11.110 8(35) cm−1, B1−B0=−0.050 71(45) cm−2u1, and D=8.5(2.6)×10−5 cm−1. (AIP)
54 citations
TL;DR: In this paper, the average lifetime of rotational levels in the A 2 Σ+−X 2 Π system of HCl and HBr+ was measured in a RF ion trap using laser induced fluorescence and time-resolved single-photon counting techniques.
Abstract: Excitation spectra in the A 2Σ+−X 2Π system of HCl+(0,0) and HBr+(1,0) as well as radiative lifetimes of selectively excited rotational levels in the A 2Σ+ electronic states have been measured in a RF ion trap using laser induced fluorescence and time‐resolved single‐photon counting techniques. Coherent ultraviolet radiation was generated by frequency mixing of a Nd:YAG/dye laser system. For HBr+ the lifetimes of four rotational levels adjacent to the v′=1 predissociation limit at J′=25/2 were measured. No statistically significant variation with J was found. The average of these four values (3.89±0.15 μs) is therefore reported as the effective lifetime of the v′=1 level of A 2Σ+ HBr+. For HCl+ the lifetime measurements likewise indicate no strong variation with J. The average lifetime of the v′=0 level of the A 2Σ+ state of HCl+ is 3.4±0.4 μs. Measurements of radiative lifetimes of molecular ions by the RF ion trap technique eliminates the determinate error that results from drift of ions out of the dete...
34 citations
TL;DR: A new modulation technique useful for high-resolution spectroscopy with tunable infrared lasers is described, demonstrated by measurements of NOupsilon = O?
Abstract: A new modulation technique useful for high-resolution spectroscopy with tunable infrared lasers is described. The high sensitivity of this method is demonstrated by measurements of NO v = 0 → 2 overtone transitions and of transitions in the fundamental band of OH with a color-center laser operating near 2.7 μm.
15 citations
01 Jan 1983
3 citations
01 Jan 1983
TL;DR: The status of molecular ion spectroscopy was elegantly reviewed by Dr. Herzberg in his Faraday Lecture to the Chemical Society [1] in September of 1971 as mentioned in this paper, where thirty-three diatomic ions and six polyatomic ions had been studied by spectroscopic methods.
Abstract: The status of molecular ion spectroscopy was elegantly reviewed by Dr. G. H. Herzberg in his Faraday Lecture to the Chemical Society [1] in September of 1971. As of that time thirty-three diatomic ions and six polyatomic ions had been studied by spectroscopic methods. All of these had been observed by absorption or emission in the visible region of the spectrum, except for H 2 + ; it had become the first molecular ion to be detected by a high resolution (better than the optical Doppler width) technique in 1968 through the work of K. B. Jefferts [2].
2 citations