Günay Başar

New energy levels and hyperfine structure measurements of neutral lanthanum by laser-induced fluorescence spectroscopy

This study is focused on the search for new energy levels and the classification of weak spectral lines by analysing hyperfine (hf) spectra. Laser-induced fluorescence spectroscopy as well as optogalvanic spectroscopy were applied to measure the hf structure of Lanthanum transitions. Free La atoms are produced and excited in a hollow-cathode discharge. Ninety-six spectral lines have been analysed in the spectral range from 430 to 742 nm using a tunable single-mode cw dye laser operating with different dyes. Ninety-four of these lines are new, which means they are not listed in commonly used wavelength tables. A classification program was used to classify these 94 lines. Eighteen new energy levels were discovered. They were confirmed by further laser excitation. Fifty-one other spectral lines were classified via their hf pattern and centre-of-gravity wavenumber from Fourier transform spectra in order to prove the new even energy levels. In addition, 31 spectral lines were observed and classified as fluorescence transitions from the excited upper levels. A total of 176 spectral lines could be classified in this work. Seventy-three magnetic dipole hf structure constants A for the upper energy levels of the transitions were determined and compared with references, if available. Twenty-three of these constants are measured for the first time (including the A constants for 18 new levels).

Hyperfine structure study of atomic niobium with enhanced sensitivity of Fourier transform spectroscopy

In an experimental setup with a high-resolution Fourier transform (FT) spectrometer and a hollow-cathode discharge, bandpass interference filters are used to enhance the sensitivity. This extension leads to an improvement of the signal-to-noise ratio in the spectrum of atomic niobium by a factor of up to 10 compared to FT spectra measured previously without filters (see Kroger et al 2010 Astron. Astrophys. 516 A70). Several additional spectral lines with low intensity have been observed. Additionally, in some intense lines, blends become visible due to the better signal-to-noise ratio. The hyperfine structure of 51 lines recorded in the wavelength range from 415 to 670 nm is analysed or re-analysed and magnetic dipole hyperfine structure constants A of 8 levels of even parity and 43 levels of odd parity are determined. Improvement of sensitivity of FT spectroscopy in the visible wavelength range enabled the determination of new hyperfine structure constants A for two energy levels of even parity, which fill the last gaps for energetically low-lying levels below 14 000 cm−1. Additionally, ten new A constants for energetically higher lying levels of odd parity as well as several improved A values have been obtained.

Experimental hyperfine structure investigation of atomic La

Optogalvanic laser spectroscopy has been applied to measure the hyperfine structure of 19 spectral lines of La I in the wavelength regions from 570 to 590 nm and 700 to 825 nm. Experimental hyperfine structure constants A and B of the isotope139La have been measured for 16 levels of odd parity. From those values six magnetic dipole and ten electric quadrupole constants have been determined for the first time. Some disagreements with previously obtained values are discussed.

High-resolution laser spectroscopy of the hyperfine structure of high-lying levels of Nb i

High-resolution laser spectroscopy techniques have been applied in the wavelength range between 645 and 675 nm to measure the hyperfine structure (hfs) of high-lying levels of atomic niobium. Using Doppler-limited optogalvanic spectroscopy 20 well-resolved spectra were measured and 10 spectra using Doppler-reduced saturation absorption spectroscopy technique. We have precisely determined the magnetic dipole hfs constants A of 42 levels and electric quadrupole hfs constants B of 15 levels. For the first time 17 A constants and 5 B constants were measured.

Isotope shift investigations in the configurations 5d9nl and 5d8nln'l' of Pt I

The isotope shift in a platinum hollow cathode discharge was studied for transitions of the type 5d97s → 5d96p, 5d97s → 5d86s6p and 5d96p → 5d86s2 through laser optogalvanic spectroscopy and high resolution interferometry. Considering configuration mixing in each of the levels of 5d96s, 5d86s2, 5d86s6p and 5d96p of all known and the new evaluated level isotope shifts, we obtain average configuration isotope shift values for the even configurations ΔT(5d96s) = 2425 (90) MHz, ΔT(5d86s2) = 5960 (60) MHz, ΔT(5d97s) = 260 (160) MHz and for the odd configurations ΔT(5d96p) = −230 (380) MHz, ΔT(5d86s6p) = 2740 (250) MHz, ΔT(5d76s26p) = 9700 (4700) MHz. These experimental values compare well with the theoretically predicted configuration isotope shifts in platinum, based on pseudo-relativistic Hartree-Fock calculations.

Hyperfine structure investigation of 187Os atomic levels via optical–optical double resonance

Optical–optical double resonance spectroscopy has been applied to measure the hyperfine structure of spectral line pairs of atomic osmium in the visible wavelength range. In the experiments, enriched isotope samples of either 189Os or 187Os were used. In this way, the magnetic dipole hyperfine interaction constants of the odd isotope 187Os were determined for seven levels of even parity and two levels of odd parity.

Investigation Of Preeclampsia By Raman Spectroscopy

Preeclampsia is associated with increased perinatal morbidity and mortality. There have been numerous efforts to determine preeclampsia biomarkers by means of biophysical, biochemical, and spectroscopic methods. In this study, the preeclampsia and control groups were compared via band component analysis and multivariate analysis using Raman spectroscopy as an alternative technique. The Raman spectra of serum samples were taken from nine preeclamptic, ten healthy pregnant women. The Band component analysis and principal component analysis-linear discriminant analysis were applied to all spectra after a sensitive preprocess step. Using linear discriminant analysis, it was found that Raman spectroscopy has a sensitivity of 78% and a specificity of 90% for the diagnosis of preeclampsia. Via the band component analysis, a significant difference in the spectra of preeclamptic patients was observed when compared to the control group. 19 Raman bands exhibited significant differences in intensity, while 11 of them decreased and eight of them increased. This difference seen in vibrational bands may be used in further studies to clarify the pathophysiology of preeclampsia.