Isotope shift studies in the UV spectrum of singly ionised gadolinium

Isotope shift Δσ(¹⁵⁶Gd-¹⁶⁰Gd) are reported for 33 spectral lines of singly ionised gadolinium (Gd II) in the 3315–3930 Å region, making use of a photoelectric recording Fabry-Perot spectrometer and highly enriched isotopic samples of ¹⁵⁶Gd and ¹⁶⁰Gd Isotope shift values for these lines have not been reported earlier. Using this data, term isotope shift ΔT(¹⁵⁶Gd-¹⁶⁰Gd) have been evaluated for the even and odd parity energy levels involved in these transitions. We report here ΔT values of only 10 odd parity energy levels lying above 35 000 cm⁻¹, which have been evaluated for the first time. Configuration assignments of six of these levels to 4f⁸6p have been confirmed and probable configurations suggested for four unassigned levels.     

Isotope shift studies in the first spectrum of ytterbium

Isotope shift △σ (172–176) have been measured in 172 lines of the first spectrum of ytterbium in the region 3900–6500 Å employing a recording Fabry—Perot spectrometer and highly enriched isotopes excited in liquid-air-cooled hollow cathodes. Out of the 172 lines studied, energy level classifications are available for 167 of them. Isotope shift △T (172–176) of 62 even and 59 odd energy levels of Yb I have been evaluated and their electronic configurations discussed.     

Isotope shift studies in the spectra of Gadolinium in UV region and term shifts of high even levels of Gd I

Isotope shift Δσ(¹⁵⁶Gd?¹⁶⁰Gd) is reported in 70 spectral lines of neutral gadolinium atom (Gd I) in the 3290- 3920 Å region providing isotope shift data in UV lines of Gd I spectrum for the first time. The measurements were carried out on a photoelectric recording Fabry-Perot Spectrometer using highly enriched isotopic samples of gadolinium. Term isotope shifts ΔT(¹⁵⁶Gd?¹⁶⁰Gd) have been evaluated for 48 high lying even parity energy levels of Gd I using this data; new ΔT values have been obtained for 24 levels. Electronic configurations 4f⁷5d6s6p, 4ff⁷5df²6p and 4f⁸5d6s assigned earlier to these even levels have been either confirmed or configuration mixing pointed out in some of these levels. Probable assignment of 4f⁸5d6s configuration to 8 even levels between 32 930 and 35 500 cm^-1 have been confirmed.     

Isotope shift in chromium

Thirty-three spectral lines of chromium atom in the blue-violet region (425–465 nm) have been investigated with the method of laser-induced resonance fluorescence on an atomic beam. For all the lines, the isotope shifts for every pair of chromium isotopes have been determined. The lines can be divided into six groups, according to the configuration of the upper and lower levels. Electronic factors of the field shift and the specific mass shift (F_ik and M_ik^SMS, respectively) have been evaluated and the values for each pure configuration involved have been determined. Comparison of the values F_ik and M_ik^SMS to the ab initio calculations results has been performed. The presence of crossed second order (CSO) effects has been observed.     

Isotope shifts in energy levels of the neutral neodymium atom

Isotope shift ΔT(142–144) have been evaluated for 281 odd and 110 even levels of the neutral neodymium atom from the isotope shift measurements made in the classified lines of Nd I spectra covering the region 3930–6510 Å. These investigations were carried out on a recording Fabry—Perot spectrometer using enriched isotopes excited in liquid-air cooled hollow cathodes. Electronic configurations of the energy levels have been discussed and probable configurations assigned to many odd and even levels. Most of the high even levels could be assigned to 4f³5d²6p configuration.     

Isotope shift in titanium atom

Isotope shifts in ten optical transitions of Ti atom have been investigated by using laser induced fluorescence on a collimated atomic beam. From the isotope shifts data, using a combined analysis with muonic atom data, specific mass shifts and field shifts have been determined and corrected values of changes of the mean square nuclear charge radii have been obtained.     

Isotope shift studies and electronic configuration assignments to the energy levels of neutral erbium

Isotope shifts ΔT (170-166) have been evaluated for 54 even and 94 odd energy levels covering almost all the known configurations of the neutral erbium. These ΔT values have been derived from the isotope shift measurements carried out in 159 lines in the region 3900–4605 A using a Fabry-Perot spectrometer and liquid-air-cooled hollow cathode source with highly enriched ¹⁷⁰Er and ¹⁶⁶Er isotopic samples. Electronic configurations assigned to energy levels of Er I by earlier workers have been mostly confirmed and in few cases revisions have been suggested on the basis of observed ΔT values. Probable configurations have been also suggested for unassigned levels of Er I, and a large number of even levels could be assigned to 4f¹¹ 5d 6s 6p configuration.     

Isotope shifts in the energy levels of the singly ionized neodymium atom

Isotope shifts ΔT (142–144) have been evaluated for odd and even energy levels of the singly ionised neodymium atom from the measurements carried out in 168 spectral lines in the 3930–5820 Å region, employing a recording Fabry-Perot spectrometer and highly enriched isotopes excited in liquid-air cooled hollow cathodes. The electronic configurations 4f³5d6s, 4f³5d6p and 4f⁴6p could be assigned to some of the energy levels on the basis of the present study.     

Isotope shift measurements in titanium I

The use of an effusive beam of titanium atoms crossed with a CW single-mode tunable dye laser has allowed the high-resolution, Doppler-free study of the isotope shifts between⁵⁰Ti,⁴⁸Ti and⁴⁶Ti, for seven 3d ² 4s ² a³ F _J 3d ² 4s 4p z ⁵ D _J , visible transitions of Ti I. The measurements show without ambiguity the existence of a non-negligible field shift. Using the values of the nuclear radii of titanium (coming from muonic X-ray measurements), it is possible to determine the respective values of the field and mass shifts.     

Isotope shift in the proton magnetic resonance of deuterated methanes

The isotope shift in the proton magnetic resonance of deuteromethanes has been examined. By the use of Pople's formula for the chemical shift, it has been shown that the effect is due to vibronic coupling from the bending modes S₄. The chemical shift was evaluated under the assumption that the hydrogen population is linearly dependent on the 2S character of the bonded carbon hybrid. Satisfactory agreement between theoretical and experimental results was obtained.     

Isotope shift of a series of Sr isotopes

We give data of the isotope shift for the strontium isotopes from A=80 to A=90. They are found to be inconsistent with data from another optical transition. Possible reasons for the discrepancy are discussed.     

Isotope shift and hyperfine structure measurements in titanium I

High accuracy measurements of hyperfine structure due to⁴⁷Ti and⁴⁹Ti in the 3d ² 4s ² a ³ F ₂?3d ² 4s4p z ⁵ D ₁ absorption line at σ=18482.772 cm^?1 have been performed by use of a Doppler-free experiment, where a beam of titanium atoms is crossed by a CW single mode tunable dye laser. They have allowed for the determination of isotope shifts between⁴⁶Ti,⁴⁷Ti,⁴⁸Ti,⁴⁹Ti and⁵⁰Ti. By use of accurate values of mean square nuclear charge radii for the even isotopes, it has been possible to separate mass shifts from field shifts and to determine accurate values for the mean square nuclear charge radii of⁴⁷Ti and⁴⁹Ti. The field shift presents a marked odd-even staggering.     

Ultrafast UV photon echo peak shift and fluorescence up conversion studies of non-polar solvation dynamics

We present photon echo peak shift and femtosecond fluorescence up-conversion studies of non-polar solvation dynamics of a simple non-polar dye p-terphenyl in ethanol and cyclohexane, using excitation in the UV range at 290 nm. The UV fluorescence up-conversion experiments were combined with a polychromatic detection and the results highlight the high sensitivity of this approach to fully characterize the excited state dynamics of the dye. We also demonstrate the feasibility of UV photon echo and transient grating and its sensitivity for the detection of non-polar solvation dynamics by measuring the frequency correlation function of the dye in the ground state. While solvation dynamics in the picosecond regime is observed in ethanol, electronic coherence dephasing occurs on timescales faster than 100 fs in ethanol as well as in the non-polar solvent cyclohexane.     

Isotope shift measurements in zirconium by Doppler-free laser polarization spectroscopy

Isotope shifts in 17 transitions of ZrI have been measured by Doppler-free laser polarization spectroscopy in a hollow cathode discharge. The results were combined with other known isotope shift data of ZrI and tested for consistency in a multidimensional King plot. By including values ofδ〈r ²〉 deduced from optical isotope shifts mass and field shifts were separated, and improved values ofδ〈r ²〉 could be determined from the King plot. The results for the isotope pairs A, A′ are as follows; 90, 92: 0.244(43) fm²; 92, 94: 0.176(20) fm²; 94, 96: 0.126(23) fm².     

Isotope shift and hyperfine structure of stable platinum isotopes

Isotope shift (IS) and hyperfine structure (hfs) measurements have been performed on seven lines of the platinum I spectrum with interference as well as laser fluorescence spectroscopy. In the latter case a frequency-doubled single-mode cw dye laser was applied. The IS of¹⁹⁰Pt with a natural abundance of only 0.01% was determined to beδν ^{190, 192}=?38.65(8) mK in theλ306.47 nm transition. The IS parameters and the effective hfs integrals in the configuration (5d+6s)¹⁰ were determined in intermediate coupling by a least squares fit of the IS and hfs data with eigenvectors obtained from the platinum fine structure (fs). The results are compared with theoretical values and yield improvedδ〈r ²〉 data.     

An anomaly in the isotopomer shift of the hyperfine spectrum of LiI

A high-precision examination of the hyperfine spectrum of 6LiI in comparison with 7LiI shows a shift in the iodine nuclear electric quadrupole moment that cannot be accounted for by a model in which the electric field gradient at the iodine site is assumed to depend only upon the internuclear distance between Li and I. The other hyperfine interactions are consistent between the two isotopomers, including the previously reported electric hexadecapole interaction of the iodine nucleus.     

HFS and isotope shift in the atomic spectrum of205Pb

The hfs of²⁰⁵Pb in the 283.3-nm resonance line and its isotope shift (IS) have been measured in absorption with the use of dispersive spectroscopy. A new method for calibration and analysis, when internal standards are not available is described. The results are: hfs interaction constantsA=70.3(5)×10^?3 cm^?1,B=?0.6(1.1)×10^?3 cm^?1,²⁰⁵Pb-²⁰⁸Pb IS=?123.9(2.0)×10^?3 cm^?1. The derived nuclear magnetic dipole moment,μ=0.704(5)μ _N is in good agreement with values calculated with a nuclear configuration mixing model.     

The UV absorption spectrum of trimethylsilyl radical in the gas phase

The UV absorption spectrum of trimethylsilyl radical was observed at 256 nm for the first time by photolysing allyltrimethylsilane and hexamethyldisilane with an ArF excimer laser. A bimolecular rate constant for recombination of trimethylsilyl radical of (2.5±0.5×10⁻¹¹ molecule⁻¹ cm³ s⁻¹ was measured.