Stark shift and broadening of FI and ClI lines

We report measured Stark shifts and widths of neutral flourine and chlorine lines. Wall stabilized arc is used as a plasma source. Electron densities 2–4×10²² m^?3 are determined from the width of theH _β line and electron temperatures 9500–10 000 K from plasma composition data. Experimental results for FI and ClI Stark widths and FI Stark shifts agree within 10% with semiclassical calculations. ClI Stark shifts are systematically smaller for about 20% than theoretical data with the only exception of the line from multiplet no. 15 where the discrepancy goes up to 49%. Results of investigation of similarities and regularities of Stark widths are in agreement with the study of Wiese and Konjevi?. Comparison of experimental Stark shifts shows certain types of regularities.     

Temperature dependence of broadening and shifts of methane lines in the ν4 band

We have recorded high-resolution absorption spectra of methane broadened by dry air and by N₂ at temperatures from −63 to 41°C using a Fourier transform spectrometer. These spectra have been analyzed to determine pressure broadening and line-shift coefficients, along with their temperature dependences, for 148 lines in the ν₄ fundamental band of ¹²CH₄. The experimental uncertainties for lines with J″≤10 are generally <2% for the broadening coefficient b⁰_L, 6–12% for its temperature dependence exponent n, 6–20% for the line-shift coefficient δ⁰, and 20–40% for its temperature dependence coefficient δ′; for J″> 10 the experimental uncertainties are somewhat larger. These results, especially for N₂-broadening, are in excellent agreement with other recent measurements. Since the present results cover a wide range of rotational quantum numbers (J″ up to 14), the variation of the temperature dependence of the half-widths and shifts from line to line within the ν₄ band is also examined.     

Measured Stark widths and shifts of the neutral argon spectral lines in 4s–4p and 4s–4p′ transitions

We investigate the Stark widths (W) and the shift (d), of the seven neutral argon (Ar I) spectral lines from the 4s–4p and 4s–4p′ transitions. The line shapes are measured in a linear, low-pressure, optically thin pulsed arc discharge at about 16 000 K electron temperature (T) and about 7.0 × 10²² m^− 3 electron density (N). The new data separates the electron width (W_e) and ion width W_i from the total Stark width (W_t), as well the separation of electron total Stark shift (d_t) on electron (d_e) and ion (d_i) parts. There are no theoretical predictions for these lines. Comparison to theoretical predictions for other lines within the same multiplets finds that the experimental data exhibits stronger influence by the ion contribution to the measured Ar I line shape. We have also deduced the ion broadening parameters which describe the influence of the ion static (A) and the ion–dynamical (D and E) effect on the width and the shift of the line shape.Applying the line deconvolution procedure, the basic plasma parameters i.e. electron temperature (T) and electron density (N) are recovered. The plasma parameters (T and N) are measured using independent diagnostics techniques as well. Good agreement is found among two sets of the N and T plasma parameters obtained from deconvolution procedure and independent diagnostics techniques.     

Stark broadening and regularities of ionized neon and argon spectral lines

Stark widths of five Ne III, five Ne IV, one Ar III and nine ArIV spectral lines have been measured in a linear-pinch discharge plasma. The results were compared with existing experimental and theoretical results, and used to establish several types of regularities. Electron densities determined with single-wavelength laser interferometry were 2.18·10²³ m^?3 and 2.80·10²³ m^?3 in neon and argon plasma, respectively. The electron temperatures determined from the Boltzmann slope of several Ne III spectral lines, and ratios of Ne III to Ne IV or Ar III to Ar IV spectral lines were 59 000 K and 42 000 K in neon and argon plasma, respectively. The investigated spectral lines originate predominantly, from 3s–3p and 3s′–3p′ Ne III and Ne IV, and from 4s–4p and 4s′–4p′ Ar III and Ar IV transition arrays. The emphasis is on the Stark width (θ) dependence on the upper level ionization potential (I), the emitter core net charge (z) and electron temperature (T) for a given electron density. This dependence was found to be of the form: θ=az ² T ^?1/2 I ^?b , wherea andb are constants within(i) several stages of ionization of neon or argon and(ii) within nitrogen like (NI, O II, F III and Ne IV) 3s–3p or phosphorus like (P I, S II, Cl III and Ar IV) 4s–4p transition arrays. The established overall trends were used to predict the Stark widths of univestigated spectral lines originating from the given transition arrays.     

Observation of forbidden (E2) lines in the ultraviolet spectra of Ca II,Sr II,and Ba II by inductively coupled plasma emission spectroscopy

Forbidden (electric quadrupole, E2) transitions of the type ns ²S_1/2–nd ²D_3/2 and ns ²S_1/2–nd ²D_5/2 in the ultraviolet spectra of singly ionized Ca, Sr, and Ba (with n = 4, 5 or 6 for Ca, Sr, and Ba, respectively) have been observed in the emission spectrum of an inductively coupled argon plasma. Wavelengths and wavenumbers of the six lines are reported and the values are in good agreement with those expected from literature data for the energy levels involved.     

Spectroscopic investigations of a cathode fall region of the Grimm-type glow discharge

This paper presents the results of the spectroscopic study of the cathode fall region of a plane cathode Grimm-type glow discharge in pure hydrogen and in argon with small admixtures of hydrogen. In contrast with the discharge in an argon-hydrogen mixture, the volt-ampere characteristics of the pure hydrogen discharge show a maximum typical for an abnormal glow-to-arc transition. This maximum in the V-A curve is explained here as being due to the increasing role of self-sputtering of the cathode material in sustaining the discharge at higher currents.For the measurements of the electric fields in the cathode fall region, Stark spectroscopy of the hydrogen Balmer lines is employed. Consistent results were obtained from H_β and H_γ recordings in a pure hydrogen discharge. Some of the difficulties in applying Stark spectroscopy for the diagnostics of a spatially inhomogeneous electric field inherent to Grimm glow discharges are discussed in detail. The experimental results are used to test the theoretical predictions of the electric field distribution in the cathode fall region. Reasonable agreement between theories and experiment is reported.Doppler spectroscopy of the same Balmer lines is used to determine the energies of the excited hydrogen atoms in the discharge. In the cathode fall region of a pure hydrogen discharge, two groups of excited atoms are detected: “slow”, in the range 3.4–8.2 eV, and “fast”, in the range 80–190 eV. The relative concentrations of “slow” and “fast” excited hydrogen atoms in the cathode fall region are determined. In addition, the relative concentration of hydrogen atoms with temperatures around 0.1 eV, excited in the plasma of the negative glow region, is also determined. The origin of these “slow” and “fast” hydrogen atoms is related to the presence of H⁺ and H₃⁺ ions, respectively. In the cathode fall region of an argon-hydrogen mixture discharge, only excited hydrogen neutrals with energies of 32–43 eV are detected. Their origin is related to the dominant role of H₃⁺ ions in this discharge. For both gases, in the negative glow region, an increase in the temperature of excited hydrogen atoms is detected, and is explained by the additional excitation of energetic neutrals in collisions with electrons.The axial intensity distributions of the hydrogen Balmer lines, in comparison with other atomic and ionic lines, show different shapes with maxima in the vicinity of the cathode surface. These shapes are explained by the excitation of reflected high-energy neutral atoms in collisions with the matrix gas.     

Line dependence of CIDEP polarizations for the p-benzosemiquinone,radical

Time-resolved steady state experiments were performed on six prominent hf-lines of the p-benzosemiquinone radical (PBQH) dissolved in ethylene glycol using an improved experimental technique. For the same six lines T₁ and _T2 were determined experimentally. Initial and radical pair polarizations as well as the second order chemical decay constant β were obtained by simulating each of the time-resolved curves using a new procedure. It was found that both the initial polarization P_a^∞(I) and β were the same within experimental accuracy for all six lines in four different experiments. The radical pair polarization P_a*, however, varied within the experimental accuracy in the manner predicted qualitatively from the theory for a second order termination reaction. Light attenuation experiments with both pulsed and continuous light confirmed these results. The magnitude of P_a^∞ (I) may be interpreted in terms of the microscopic theory for the photo-activated triplet mechanism, whereas the magnitude of P_a* appears to be too high by a factor of four to six as compared to the microscopic theory for the radical pair mechanism.     

Classification of 3-3 transitions in neonlike germanium in laser-produced plasma

Classification of 3-3 transitions in neonlike germanium in laser-produced plasma has been made. The spectra have been observed in the range of 185–290 Å using a high resolving power (λ/Δλ ～ 13000) grazing-incidence spectrometer in XUV laser experiment. A total of 21 lines (including five lasing lines) have been classified as transitions between the 2s ²2p ⁵3s, 3p, 3d or 2s2p ⁶3p, 3d and sodiumlike germanium configurations. The identified transitions have been used to derive energy levels of 2s ²2p ⁵3l in neonlike germanium. The experimental results have been compared with theoretical predictions from Dirac-Fock (MCDF) calculations.     

Characterization of Interactions Between Fluoroquinolones and Human Serum Albumin by CE–Frontal Analysis

The binding of fluoroquinolones to the transport protein, human serum albumin (HSA), under simulated physiological conditions has been studied by capillary electrophoresis–frontal analysis (CE–FA). The binding of these drugs to human plasma was evaluated by using ultrafiltration and capillary electrophoresis. The free drug concentration [D]_f at each HSA concentration was determined by the plateau height in the electropherograms and the calibration lines. The binding constants of fluoroquinolones and HSA were estimated using nonlinear regression with origin 7.5 software. The fluoroquinolones were found to show low affinity toward HSA, with binding constants ranging from 1.73 × 10² to 5.40 × 10² M^?1. The percentages of protein binding (PB) for fluoroquinolones to HSA were between 8.6 and 22.2%, while the PB percentages for fluoroquinolones to human plasma were between 10.2 and 33.1%. It can be found that the PB percentages for fluoroquinolones to HSA are mostly lower than those for fluoroquinolones to human plasma. It suggests that HSA is the primary protein responsible for the binding of fluoroquinolones in human plasma. The thermodynamic parameters were obtained by CE–FA. The positive ?H and ?S values obtained by CE–FA showed that the binding reaction was an endothermic process, and the entropy drive the binding and hydrophobic interaction played major roles in the binding of fluoroquinolones to HSA.     

o-phthalic acid as a standard substance for calibrations of hydrogen ion concentrations with a glass electrode

o-Phthalic acid is proposed as a standard substance for buffer solutions of known hydrogen ion concentration (I ? 0.2 M KCl, p[H⁺] = 3.0–5.4, 25°C). Its crystallinity, purity and slightly wide buffer range afford advantages over acetic acid. Empirical relationships between measured pH (pH_m) and calculated [H⁺] were derived for sequences of buffer solutions at several ionic strengths: pH_m - Mp[H⁺] + C. These calibration lines were parallel and of unit slope as required by theory. A table of p[H⁺] values for o-phthalic acid buffer solutions at I = 0.1 M (KCl) is presented and the method of calculation of p[H⁺] values for a buffer series generated by additions of potassium hydroxide is outlined.     

GC–MS Measurement of 13C-Enrichment of Lactic Acid in Sepsis Plasma

Sepsis is a systemic inflammatory response syndrome arising from infection. The plasma lactic acid level is a reliable marker of sepsis. A novel procedure based on microwave-assisted derivatization followed by gas chromatography–mass spectrometry (GC–MS) has been developed for the rapid measurement of ¹³C-isotope enrichment of lactic acid in plasma. The derivatization conditions and method validation were studied. The method was applied to the measurements of isotopic enrichment of lactic acid in the plasma of a rabbits which had received the tracer ([1,2,3-¹³C₃] lactic acid) by carotid infusion 2.5 h before blood sampling from the portal vein. These results show that the proposed method has excellent precision (RSD less than 4.57%), linearity (slope = 0.9936; r ² = 0.9998), accuracy and selectivity. The analytical results show that microwave-assisted derivatization coupled to GC–MS is a rapid method for the direct isotopic measurement of deproteinised plasma. The method could be of great interest for metabolic studies in animal models and human patients.     

Analysis of anomalous vibrational and rotational distributions in the CN(B2Σ+) state produced in the reaction of Ar(3P0,2) metastables with BrCN

The CN(B²Σ⁺ - X²Σ⁺) tail band emission system for μ′ = 11–20 resulting from the energy transfer reaction Ar(³P_0,2) + BrCN in a flowing afterglow apparatus was measured. The vibrational and rotational distributions were determined as a function of argon pressure. Numerous perturbed rotational lines were observed; analysis of the dependences of these lines on argon pressure, with the aid of experimental information already published, led to the following assignments as to the origins of the perturbations: For μ′ = 11, N′ = 20 and μ′ = 13, N′ = 9, the perturbing state is a ⁴Σ⁺; for μ′ = 12, N′ = 10 and 14, μ′ = 14, N′ = 7 and 10, and μ′ = 17, N′ ≈ 17–19 the perturbing state is A ²Π_i. The perturbed rotational line, μ′ = 11, N′ = 20, is found to be the primary source of intensity in the μ′ =11 vibrational band, but in all other cases the perturbed rotational lines do not significantly aid in the populating of the vibrational state. The anomalously high vibrational populations found in the tail band emission system (μ′ = 12, 14, 17 and 18), as well as the significantly high rotational excitations observed in the μ′ = 12–20 vibrational bands, apparently arise directly from the reaction intermediate.     

Validated LC Determination of the Piroxicam-β-Cyclodextrin Inclusion Complex in Tablets and in Human Plasma

A simple, rapid, specific, sensitive HPLC method has been developed for the determination of piroxicam in the tablet dosage form and in human plasma. The method totally eliminates solvent extraction and time-consuming separation procedures. Plasma proteins were precipitated by addition of 3:1 (v/v) acetonitrile-methanol, ZnSO₄, and MgSO₄ and the supernatant was injected directly on to a 250 mm × 4.6 mm, 5 μm particle Spherisorb analytical column. Acetonitrile-methanol-0.04 mol L^?1 KH₂PO_4, 40:10:50 (v/v); pH 3.8, was used as mobile phase. The drug was detected by UV detection at 330 nm. The response was linear over the range of 0.01–10 μg mL^?1 and 0.025–5 μg mL^?1 in mobile phase and human plasma samples, respectively. The proposed method was used without interference from the endogenous substances, for determination of piroxicam in plasma samples obtained from healthy volunteers. The results revealed that the method would be useful in monitoring plasma levels of the drug during pharmacokinetic studies. Assay of piroxicam in its dosage forms for quality-control purposes could also be performed successfully by use of this method.     

Some spatial effects observed in the axially viewed filament argon microwave induced plasma with solution nebulization

Spatial profiles of analyte emission in an axially viewed argon filament microwave induced plasma sustained in the TE₁₀₁ rectangular cavity have been measured along a discharge tube cross-section for neutral atoms as well as ion lines of several elements. The filament diameter was approximately 1 mm. The analyte solution was introduced by means of an ultrasonic nebulizer without desolvation. The radial emission distribution depends on the operating parameters and is different for each of the analytes examined. Spatial distributions of excitation temperature (4000–6000 K) measured with Ar I lines by the Boltzmann plot method as well as electron temperature (6000–8000 K) by line to continuum emission ratio measurements at Ar I 430 nm and electron number density (1–1.5×10¹⁵ cm⁻³) by the Stark broadening method of the H_β line were determined to support the evidence of plasma processes. In the presence of excess sodium the enhancement of emission intensity and its shift to the plasma center appears to be the result of increased analyte penetration to the plasma. Changes in spatial emission profiles for Ca atoms and ions suggest that for this element ambipolar diffusion may be important as an additional interference mechanism. A possibility of minimizing spectral interferences from argon emission lines by choosing an off-axis plasma region for emission intensity measurements is indicated.     

Charge transfer reactions between xenon ions and iron atoms in an argon-xenon inductively coupled plasma

Xenon is added to the axial channel of an argon inductively coupled plasma (ICP) at doses up to 1.5% of the aerosol gas flow. Emission is collected from the gas flowing into the sampling orifice of a mass spectrometer (MS). These Xe doses have little effect on the electron density n_e or on the intensities of Fe (I) emission lines. Certain Fe (II) lines are enhanced when Xe is added, particularly those from Fe⁺ states that can be populated by near-resonant charge transfer between Xe⁻ and neutral Fe. Calculations based on measured values of n_e indicate that Xe⁺ should be present at densities of up to 7 × 10¹⁴ cm⁻¹, which should be sufficient Xe⁺ to drive the proposed charge transfer reactions.     

Translational energy distributions and production mechanisms of the excited hydrogen atom (n = 3,4) produced in e-NH3 collisions

The Balmer α and β lines produced in e-NH₃ collisions have been measured precisely with the use of a Fabry-Perot interferometer. These lines are not polarized. The translational energy distributions of (H^*(n = 3,4) were determined from analysis of Doppler lineshapes and have five components; their peaks lie at 1, 3, 2, 4–5 and 8–12 eV. The excitation function [H^*(n = 4)] has five thresholds at 22.5, 29.0, 33.3, 38.9 and 41.7 eV, and indicates that five dissociation processes contribute to the formation of H^*. Excitation to the Rydberg states converging to the (2a₁)^?1 state of NH₃⁺ is a major process for the formation of the first and the second components. Doubly excited Rydberg states play important roles in the dissociative excitation of NH₃.     

Optical absorption and EPR spectroscopic studies of (30 − x)Li2O–xK2O–10CdO–59B2O3–1Fe2O3: An evidence for mixed alkali effect

Optical absorption and EPR spectroscopic studies were carried on (30 ? x)Li₂O–xK₂O–10CdO–59B₂O₃–1Fe₂O₃ (x = 0–30) glass system to understand the effect of progressive doping of Li⁺ ion with K⁺ ion. Optical absorption results show typical spectra of Fe³⁺ ions and the various optical parameters such as, optical band gap, Urbach energy, oxide ion polarizability, optical basicity and interaction parameter were evaluated from the experimental data. The observed optical band gap and Urbach energy values show large deviation from the linearity where as the other parameters show small deviation from the linearity with the progressive substitution of Li⁺ ions with K⁺ ions. The observed EPR spectra are representative of Fe³⁺ ion in octahedral and axial fields in the glass network. The number of paramagnetic centers and paramagnetic susceptibility values were evaluated at different resonance lines for all the specimens and these parameters show non-additive nature with the progressive substitution of Li⁺ ions with K⁺ ions in the glass network. This is first ever observation of mixed alkali effect (MAE) in EPR and optical parameters of mixed alkali borate glasses.     

Asymmetric Stark broadening of the Fe I 538.34 nm emission line in a laser induced plasma

In this work asymmetries along with shifts in the line profiles of neutral iron emission lines coming from a laser induced plasma have been detected. The plasma was produced in air at atmospheric pressure on a 50% Fe–Ni alloy and the emission was collected at a temporal window of (2.5, 3) μs. To avoid the effect of spatial inhomogeneity on the profiles, a deconvolution procedure was applied to obtain the spatially resolved emissivity. Asymmetric theoretical Stark profiles, which take into account the effect of static ions, were used to be fitted to the experimental data of the emission profile of the line Fe I 538.34 nm. The fitting of the theoretical profile to the experimental data was carried out by means of the least squares method using genetic algorithms to automatically solve the optimization problem. The correlation coefficient was higher for the asymmetric fits than for the symmetric ones. From the fit, the quasistatic ion broadening parameter α, the electron broadening parameter w_e, and the total shift of the maximum of the line d_t, were obtained. The ion parameter α varied in a range (0.2–0.3) for an electron density between (4–15) × 10¹⁶ cm^− 3. The ion influence on the total broadening was of 15–20%. The total shift varied in the range (0.01–0.06) nm and it was mainly given by the ion shift, the electron shift being negligible. For the electron density range in this work, approximated linear behaviors of the total width and shift with electron density have been obtained.     

Rapid and Sensitive RP-LC Method for the Quantification and Pharmacokinetic Study of p-Hydroxyphenethyl Anisate in Rat Plasma

A rapid, sensitive and specific reversed-phase liquid chromatographic method was developed and validated for the quantification of p-hydroxyphenethyl anisate (HPA), which is one of the main constituents of Notopterygium Radix (underground parts of Notopterygium incisum and N. forbesii), in rat plasma, and study its pharmacokinetics after the intravenous administration of 40 mg kg^?1 HPA to rats. The method involves a plasma clear-up step using liquid–liquid extraction by ethyl acetate, followed by RP-LC separation and detection. Separation of HPA was performed on an analytical Diamonsil ODS C₁₈ column equipped with a Dikma ODS C₁₈ EasyGuard column using a mobile phase consisting of MeOH–H₂O (75:25, v/v) at a flow-rate of 1.0 mL min^?1. The UV detection was performed at a wavelength of 256 nm. The linear calibration curves were obtained in the concentration range of 0.05–5.0 μg mL^?1 (r = 0.9992, n = 5) in rat plasma with the lower limit of detection of 0.01 μg mL^?1 and the lower limit of quantification of 0.04 μg mL^?1, and the extraction recovery of HPA was calculated to be the range of 82.01–86.66%. The intra- and inter-day precisions in terms of % relative standard deviation were lower than 2.33 and 3.99% in rat plasma, respectively, with accuracies ranging from 91.22 to 110.5%. The developed method was suitable for the determination and pharmacokinetic study of HPA in rat plasma.     

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.