Nicolo Acquista

Spectroscopy of Fluorine Flames. I. Hydrogen‐Fluorine Flame and the Vibration‐Rotation Emission Spectrum of HF

The hydrogen fluoride vibration‐rotation emission spectrum from a hydrogen‐fluorine diffusion flame has been studied under high dispersion from 3200 cm−1 in the infrared to about 5500 A in the visible. Measurements were made on the rotational lines in 23 bands including (1–0), (2–1), and (3–2) of the Δv=1 sequence; (2–0), (3–1), (4–2), (5–3), and (6–4) of Δv=2; (3–0), (4–1), (5–2), and (6–3) of Δv=3; (4–0), (5–1), (6–2), (7–3), (8–4), and (9–5) of Δv=4; and (5–0), (6–1), (7–2), (8–3), and (9–4) of Δv=5. Complete rotational and vibrational analyses were carried out. The constants Bv, Dv, and Hv are given for v=0 to 9. The data were extensive and precise enough to warrant an extended Dunham treatment from which 18 coefficients could be determined, including those for terms in (v+½)5 and J4(J+1)4. Band centers for 22 bands and the vibrational term values Ev for v=0 to 9 are given.

Emission spectrum of CF

Abstract The A2Σ+-X2Π system of CF has been investigated with high dispersion in the region 2190–2965 A and the rotational structure of 18 bands analyzed. Vibrational and rotational constants have been determined for levels up to v′ = 1 and v″ = 9. The rotational analysis was carried out in part with the help of a digital computer program which searched wave-number lists for rotational branches. Consideration of potential curves and dissociation energies indicates that, in the first approximation, the potential curve of the stable A state is crossed by a repulsive curve of the same symmetry. However, application of the noncrossing rule results in the formation of two stable excited states. The lower state, which is the A2Σ+ state, must therefore have a potential maximum which can be located just above v′ = 2 and must undergo rotational predissociation. The other state may be identified as the previously known B state whose character must then be 2Σ+ also. The ground-state dissociation energy is found by extrapolation to be 5.50 ± 0.10 eV; this in turn leads to an estimate of 2.06 ± 0.10 eV for the B 2 Σ + state.

Infrared Spectra of HCl, DCl, HBr, and DBr in Solid Rare‐Gas Matrices

The infrared absorption spectra of HCl, H35Cl, DCl, HBr, and DBr isolated in solid rare‐gas matrices in the range 4°—20°K are presented. The influence of temperature, dilution, deposition rate variations, as well as the presence of certain impurities, on the spectra are also reported and discussed.In the fundamental region the spectra normally consist of a few relatively narrow bands or lines which show reproducible and fully reversible variation of intensity and bandwidth with change of temperature. The presence of certain dopants, e.g., N2, in the halide—noble‐gas mixture leads, under suitable deposition conditions, to the replacement of the temperature‐dependent features by much narrower temperature‐insensitive lines at somewhat shifted frequencies.The temperature‐dependent features have been identified as individual rotation—vibration lines of the matrix‐isolated diatomic molecules. Their separations are significantly less than those of the corresponding lines in the free molecule spectra, thereby ind...

STRUCTURE OF THE ALKALI HYDROXIDES. V. THE INFRARED SPECTRA OF MATRIX- ISOLATED RbOH, RbOD, NaOH, AND NaOD.

The infrared spectra of matrix‐isolated RbOH, RbOD, NaOH, and NaOD have been observed. Both the alkali‐metal–oxygen stretch ν1 and the bending mode ν2 have been assigned for each species. The metal–oxygen stretching mode is found at 354.4, 345, 431, and 422 cm−1 for RbOH, RbOD, NaOH, and NaOD, respectively; the bending mode ν2 is observed at 309.0, 229, 337, and 250 cm−1, respectively. Combination of the results of this study with the microwave measurements for RbOH and RbOD indicates an essentially linear structure for these species. The isotope shift for ν2 observed in NaOH coupled with reasonable bond lengths indicates an equilibrium configuration of NaOH which probably does not deviate significantly from linearity. The assumption of a linear model with a harmonic bending potential yields force constants of 0.046 × 10−18 and 0.053 × 10−18 Nm (0.046 and 0.053 mdyn·A) for RbOH and NaOH, respectively. These results are consistent with our previously reported results for CsOH.

Spectrum and energy levels of thirteen-times ionized molybdenum (Mo XIV)

The spectrum of Mo xiv was observed with a low-inductance spark and a laser-produced plasma in the region from 70 to 630 A on the10.7-m grazing-incidence spectrograph at NBS. From the identification of 35 lines, a system of 22 energy levels was determined. The level system (Cu i isoelectronic sequence, 3d10nl) includes the series ns (n = 4–6), np (n = 4–6), nd (n = 4,5), nf(n = 4–6), and ng (n = 5–7). The observed energy levels are compared with Hartree-Fock calculations. The ionization energy is determined from the ng series (n = 5–7) to be 2 440 600 ± 300 cm−3 (302.60 ± 0.04 eV).

Atlas of the spectrum of a platinum/neon hollow-cathode reference lamp in the region 1130-4330 Å

The spectrum of a platinum hollow-cathode lamp containing neon carrier gas was recorded photographically and photoelectrically with a 10.7 m normal-incidence vacuum spectrograph. Wavelengths and intensities were determined for about 5600 lines in the region 1130–4330 Å. An atlas of the spectrum is given, with the spectral lines marked and their intensities, wavelengths, and classifications listed. Lines of impurity species are also identified. The uncertainty of the photographically measured wavelengths is estimated to be ± 0.0020 Å. The uncertainty of lines measured in the photoelectric scans is 0.01 Å for wavelengths shorter than 2030 Å and 0.02 Å for longer wavelengths. Ritz-type wavelengths are given for many of the classified lines of Pt II with uncertainties varying from ±0.0004 to ± 0.0025 Å. The uncertainty of the relative intensities is estimated to be about 20%.

4s 2 1 S 0 –4S4p 1 P 1 transitions in zinclike ions

The 4s/sup 2/ /sup 1/S/sub 0/-4s4p/sup 1/P/sub 1/ transitions of 20 zinclike ions from Ru/sup 14 +/ to Du/sup 36 +/ were observed in a laser-produced plasma with a 10.7-m grazing-incidence spectrograph. Also, new observations were made of the 3d-4f transitions of Fe/sup 15 +/. Based on the new wavelengths obtained for these Fe transitions and improved wavelengths recently published for other Fe ions, revised values were determined for the 4s/sup 2/ /sup 1/S/sub 0/-4s4p/sup 1/P/sub 1/ transitions in ten zinclike ions from Ba/sup 26 +/ to W/sup 44 +/ observed by Reader and Luther (Phys. Rev. Lett. 45, 609-613(1980)) for which a laser-produced spectrum of Fe was used for wavelength calibration.

Infrared Spectrum of the Matrix‐Isolated OH Radical

Infrared absorption in the region of 3450 cm−1 has been observed in water–rare‐gas matrices subjected to vacuum‐ultraviolet photolysis at 20.4° and 4.2°K. The splittings and isotope frequency ratios obtained from H216O–D216O, H216O–H218O, and D216O–D218O mixtures lead to the assignment of these spectra to trapped OH radicals. No evidence for rotational motion of OH is found in these experiments.

Structure of the Alkali Hydroxides. II. The Infrared Spectra of Matrix‐Isolated CsOH and CsOD

The infrared spectra of matrix isolated CsOH and CsOD have been observed. Both the CsO stretching and the bending mode have been assigned for each species. The Cs–O stretching mode ν2 is observed at 335.6 and 330.5 cm−1 for CsOH and CsOD, respectively; the bending mode ν2 is observed at 306 and 226 cm−1, respectively. Combination of the infrared results with previous microwave measurements indicates that the equilibrium configuration of CsOH probably does not deviate significantly from linearity. The assumption of a linear model with a harmonic bending potential leads to a bending force constant of 0.047 mdyn· A.

Spectrum and energy levels of ten-times ionized yttrium (Y xi)

The spectrum of Y xi was observed with a low-inductance vacuum spark and a laser-produced plasma in the region from 70 to 630 A on the 10.7-m grazing-incidence spectrograph at NBS. From the identification of 40 lines, a system of 29 energy levels was determined. The level system (Cu ii isoelectronic sequence, 3d10nl) includes the series ns (n=4 –7), np (n=4–6), nd (n=4–6), nf (n =4 – 7), and ng (n =5–8). The 4f2F term is inverted. The observed energy levels are compared with Hartree-Fock calculations. The ionization energy is determined from the ng series (n =5 – 8) to be 1 660 000 ± 200 cm−1 (205.82 ± 0.03 eV).