Argon Laser Lines Research Articles

Electric-field controllable photoluminescence in porous silicon

Intense photoluminescences (PL) at wavelenghts near 600 nm are observed when either the (100) or (111) surface of the electrochemically etched silicon wafers are illuminated by the 514.5 nm argon laser line. A fascinating phenomenon has been discovered indicating that the PL intensity can be suppressed exhaustively by applying an electric field parallel to the surface. The PL recovers its intensity very slowly when the bias is taken off, suggesting that the slow relaxation of the accumulate charges inside the porous silicon.

Surface-Enhanced Raman Scattering (SERS) Study of the Interaction between Hematoporphyrin and Guanine

The interaction between hematoporphyrin and guanine has been investigated by the Raman spectroscopic method. Irradiation of guanine solution mixed with hematoporphyrin was observed through the change in the Raman spectra. It was observed that the band at 1534 cm−1 shifted and the bands at 1274 cm−1 and 1190 cm−1 disappeared in the presence of hematoporphyrin. A prolonged irradiation time of five hours caused the SERS spectra of guanine to disappear. These results indicate that the guanine was modified in the photosensitized reactions in the presence of hematoporphyrin. We used SERS to study the photodynamic modification of nucleic acid base by hematoporphyrin. We found that illumination of guanine and adenine with the 514.5-nm argon-ion laser line in the presence of hematoporphyrin resulted in the selected degradation of guanine.

Reversed-phase liquid chromatography of the opioid peptides. 3. Development of a microanalytical system for opioid peptides involving microbore liquid chromatography, post-column derivatization and laser-induced fluorescence detection

A microanalytical system has been developed for the determination of peptides in small samples. Naphthalene-2,3-dicar☐aldehyde-β-mercaptoethanol (NDA—BME) was used as the labelling reagent system as an alternative to NDA—cyanide (NDA—CN) because of the faster labelling when CN was replaced by a thiol. The fluorescence characteristics of the NDA—thiol adducts, N-substituted 1-alkylthiobenz[f]isoindoles (TBIs), were found to be different from the previously described cyanobenz[f]isoindole (CBIs) adducts formed by the reaction of primary amines with NDA—CN. The excitation maximum of the TBI adducts was at 460 nm, which was closer to the 457.9 nm argon-ion laser line, than the 440-nm maximum of the CBI adduct. The limit of detection for leucine enkephalin was 36 fmol ( S/N = 3) and linearity was proven for greater than 2 orders of magnitude, from 45 fmol to 9 pmol for an injection volume of 60 nl. The detectability was limited by the high background noise produced by the post-column derivatization system. The utility of the system was demonstrated for the analysis of methionine enkephalin and its potential oxidation products, using leucine enkephalin as a suitable internal standard.

Photodeposition of thin cadmium films from CdS colloid solutions

A new liquid-phase photodeposition process of cadmium thin films from aqueous cadmium sulphide colloid solutions has been developed. In this process, the photoexcitation of CdS colloid particles causes the formation of elementary cadmium which is partly precipitated in the bulk of the photoreactor and partly adsorbed on the reactor optical window, creating thin films. The initial photodeposition growth rates are small, indicating an adsorption-controlled process. The continuation stage growth is much faster and also thermally activated. The quantum yield increases by several orders of magnitude from visible (514 nm) to UV (366 nm) radiation. The adsorption affinity of photo-precipitated cadmium particles is highest for cadmium material sites on the substrate. Onto UV pre-deposits, ultrathin films could efficiently be grown with visible argon laser lines. Preliminary image recordings indicate the potential use for high resolution cadmium thin film pattern applications.

A symmetry principle for corresponding Stokes and anti-Stokes continuum resonance Raman scattering

We have recorded high resolution Stokes and anti-Stokes continuum resonance Raman spectra of iodine and isotopically pure iodine bromide with excitation by several argon ion laser lines in the blue to the green spectral region. For specific excitation frequencies the intensities of Stokes and anti-Stokes continuum resonance Raman lines agree well with each other in accordance with a general symmetry relation. The latter is interpreted in detail applying numerical calculations based on time dependent as well as time independent second-order perturbation theory.

Bistable optical device realization with thin Cds films

A thin (6 μm) CdS film thermally laser induced optical device (LIOD) was realized at 210 K using the 514.5 nm argon laser line. It is demonstrated for the first time that the observation of equally contrasted all optical (all-OB) and hybrid (HB) bistable loops is possible in thin CdS films. Furthermore, it is pointed out that the photocurrent dependence on temperature is different in sprayed and evaporated CdS films resulting in opposite HB loop fashions: clockwise for the sprayed and anti-clockwise for the evaporated thin films.

Improved BrdUrd-Hoechst bivariate cell kinetic analysis by helium-cadmium single laser excitation.

In laser based flow cytometers, UV excitation of Hoechst 33258 and propidium iodide (PI) or ethidium bromide (EB) is performed with 351/364 nm high power lines of UV-capable argon ion lasers, which are expensive and short-lived. In this paper we note for the first time that helium-cadmium lasers emitting 10 to 30 mW at 325 nm are even more superior for cell kinetic bivariate bromodeoxyuridine (BrdUrd)/Hoechst PI or EB cell cycle analysis. HeCd single laser UV excitation gives comparable CVs for cell cycle distributions, and almost normal G2M/G1 ratios of 1.9 to 2.0 for all cell cycles. This is shown for synchronous and asynchronous cell populations on a FACStar+ and an Ortho Cytofluorograf. Therefore we recommend helium-cadmium lasers as low-power, cheap, and long-lived UV excitation sources for the cytochemically simple but high resolution multiparameter BrdUrd-Hoechst cell kinetic analysis.

RAMAN SPECTRA OF SEVEN INTERPLANETARY DUST PARTICLES

The Raman shift spectra of seven interplanetary dust particles, U2034(F10), U2034(F8), U2022(B1), W7074 18, W7074 C15, W7074 C3 and W7074 A7, were measured with a Spex-1403 Raman spectrograph. The exciting radiations were the 488 nm and 514 nm line of a 5W argon ion laser. All seven spectra exhibit the 1350 and 1600 Delta/cm arbon bands, implying that the Interplanetary dust particles were coated with hydrocarbon and incompletely crystallized carbon, the part of which may be the residue of hydrocarbon contents in the particles after water loss by the heating during their entry into the earth's atmosphere. A weak band structure in the 520-610/cm range could be caused by cyclosilicates, and a weak band at 2900/cm is tentatively identified as due to hydrocarbon molecules.

Fourier transform spectroscopy of the 1 3Δ g- b3Π u transition in 6Li 2

The 1 3Δ g- b 3Π u transition of 6Li 2 has been observed in collisionally induced fluorescence following (a) excitation of the C 1Π u state by the ultraviolet lines of argon and krypton ion lasers and (b) single frequency double resonance excitation of the F 1Σ g + state using a ring dye laser operating with DCM dye. Spectra were obtained at high resolution using Fourier transform spectrometers. Many lines are broadened and shifted because of predissociation of b 3Π u by a 3Σ u +; the widths and shifts have been measured as a function of rotation and vibration. Several perturbations have been observed in the 1 3Δ g state and are shown to be caused by interaction with the 2 3Π g state. The data are reduced to molecular constants (Dunham coefficients), perturbations are analyzed, and the collisional mechanism responsible for excitation of the 1 3Δ g state is discussed.

Analysis of Aerosol Particles by Resonance Raman Scattering Technique

An analytical technique for aerosol samples which utilizes the resonance Raman effect is described. The aerosol particles were generated at 50 kHz by a vibrating orifice. The nominal particle size was 45 µm in diameter. The visible lines (4579, 4765, 4880, and 5145 Å) of a continuous argon-ion laser were used as the excitation source. Within the coverage of the laser wavelengths, effects of pre-resonance, resonance, and post-resonance Raman scattering were studied. Under the resonance condition, the enhancement of p-nitrosodimethylaniline is 5.5 × 104 when compared to that of nitrate ions. The corresponding concentration of detection limit is 10−6 molar.

Effect of Laser Illumination on Oxidization of Porous Silicon

ABSTRACTWe have studied the effect of laser illumination (argon laser line of 488 nm) on the oxidization process of the inner surfaces of porous silicon (PS) by measuring the photoluminescence (PL), Fourier-transform infrared (FTIR) absorption and x-ray photoelectron spectroscope and contrasted the variations of PL and FTIR spectra of the PS treated in the following four ways: 1. In vacuum with laser illumination (LI) with power density of 12 mW / mm2. 2. In oxygen with LI. 3. In oxygen without LI. The times for all the above three treatments were 1 h. 4. Storage in air for 2 months without LI. The PL peak of PS showed serious degradation and a blue shift in case 2 but only a moderate degradation and no shift in case 1. The results of FTIR absorption show that the LI in an atmosphere of oxygen enhanced greatly the increase of oxygen-related absorption bands and the decrease of various silicon-hydrogen vibrational mode absorption bands.

Visible-laser-induced chemiluminescence of NaHg red excimer bands

Visible argon ion laser lines were used to induce the chemiluminescence of the NaHg excimer. Sodium dimers, excited into theB 1Π u state, produced in reactive collision with Hg atoms the NaHg excimers in the first excited electronic states. A qualitative analysis of the origin of the observed spectra, based on ab initio NaHg potential curves calculations, is presented.

Polarized and depolarized continuum resonance Raman scattering of molecular iodine: accurate determination of repulsive states

We have recorded high-resolution polarized and depolarized resonance Raman spectra of molecular iodine with excitation by argon-ion laser lines at 496.5, 488.0, and 476.5 nm up to the seventh, and with 457.9 nm up to the fifth, overtone. These spectra were also calculated numerically applying second-order perturbation theory. In contrast to earlier publications on this subject, special emphasis was put on obtaining highly reliable polarized and depolarized spectra. The variations of the spectral band shapes and depolarization ratios obtained at different excitation wavelengths could be explained by means of the specific contributions of the two excited electronic states [Formula: see text] and 1П1u. About 60 different experimentally obtained spectra were finally used to derive the positions of the two excited-state potentials involved in this type of light scattering. The derivation was done by comparison of the experimental and theoretically simulated spectra where parameters of the 1П1u as well as of the [Formula: see text] state potentials were varied. Key words: resonance Raman scattering, diatomic molecules, potentials, excited electronic states.

Determination of excited state potential functions from continuum resonance Raman scattering: Excitation of 79Br2 from the visible to the UV region

AbstractHigh‐resolution polarized and depolarized resonance Raman spectra of isotopically pure molecular bromine (79Br2) with Δν = 1–5 were recorded using the argon laser lines at 501.7, 496.5, 488.0, 476.5, 457.9, 363.8, 351.1 and 333.6 nm and the Kr laser line 413.1 nm. Using a high‐sensitive CCD camera, the experimentally obtained spectra have better signal‐to‐noise ratios than some of the spectra already published. All observed spectra were also calculated using second‐order perturbation theory. The high sensitivity of resonance Raman band shapes to changes in the position of excited potential curves gives the possibility of determining the potential functions of the excited states 1II1u and 3II0+u in the energy range between 20 000 and 30 000 cm−1 very accurately. These potentials allow a satisfactory description of all observed spectra, including those of the overtones, in contrast to earlier work.

Polarized and depolarized Raman scattering of 35Cl2 with excitation from the visible to the ultraviolet region

We have recorded high-resolution polarized and depolarized Raman spectra of isotopically pure 35Cl2 using the argon ion laser lines 501.7, 496.5, 488.0, 476.5, 457.9, 363.8, 351.1, and 333.6 nm and the krypton ion laser line 413.1 nm. Overtone progressions can be observed for 413.1 nm and UV excitation. The spectral band shapes of the overtones show a systematic variation with excitation frequency. The relative intensities of the overtone bands have been calculated with second order perturbation theory. The spectral feature of the overtones can be explained by resonance Raman scattering via the repulsive 1Π1u state. The 1Π1u potential was determined with a high accuracy. This is possible because the Raman band intensities are very sensitive to the location of the potential curves of the involved excited scattering states. The spectral feature of the fundamental band excited in the UV region can be explained assuming a destructive interference effect between resonant and nonresonant Raman scattering resulting from adjacent highly lying states. This effect can be monitored via the depolarization ratio of the fundamental transitions, the change in relative intensities between the different Q branches of the fundamental bands and comparison of the observed and calculated overall band intensities of the fundamental and overtone bands excited with different laser lines.

The (3s, 3d) 1Δ g electronic state of Na 2

Ultraviolet lines of both krypton-ion and argon-ion lasers excite levels in the C(2) 1Π u state of Na 2. Following efficient collisional transfer to (1) 1Δ g, the (0—0) sequence of the (1) 1Δ g—B(1) 1Π u system appears strongly in the infrared around 7020 cm −1. High-resolution Fourier transform spectra have been analysed to derive constants of the 1Δ g state, for which T e=27338.46 cm −1. Its properties, with ω e=130.0 cm −1, B e=0.1255 cm −1, D e=7857 cm −1, and a quantum defect of almost zero, are some way from those of a pure Rydberg state.

Spectral Study of Caesium Dimer Excited with 476.5, 472.7, 465.8 and 457.9 nm Argon Ion Laser Lines

Spectral Study of Caesium Dimer Excited with 476.5, 472.7, 465.8 and 457.9 nm Argon Ion Laser Lines

Optical gain on the 476.5 nm Argon-ion laser line in a gas-target excited by a heavy ion beam

Optical gain on the 476.5 nm Ar II 4p−4s ion laser transition has been observed in argon-gas excited by 2.5 ns pulses of 90 MeV32S ions with a repetition rate of 4883 Hz. The energy per pulse was 23 μJ. The projectiles were stopped in the target at pressures between 5 and 20 kPa. Gain was determined from a measured transient increase of the intensity of a 476.5 nm probe laser beam sent along the ion beam axis and back reflected by an aluminum foil. The maximum gain observed was (0.4±0.1)×10−3 at a target-gas pressure of 5 kPa. Control experiments using krypton as target-gas were performed and yielded a null result. The optical gain observed in argon is consistent with the result from an analysis of spectroscopic studies of rare-gas targets excited by heavy ion beams.

Lifetime measurements of Cs 2 molecules excited by laser pulses at 476.5 nm

The lifetime of Cs 2 molecules excited with the 476.5 nm line of a mode-locked argon ion laser are determined. The fluorescence decay is found to consist of three exponential components with lifetimes τ 1≈29 ns, τ 2≈4.5 ns and τ 3⩽1 ns respectively. The fluorescence is interpreted as originating from the E' 1Π u state perturbed by the bound (3) 3Π u state and the repulsive (3) 3 ∑ u state.

Luminescence Spectrum of Trivalent Terbium Ions Adsorbed on a Single Resin Bead

We report a partial luminescence spectrum of terbium (III) adsorbed on a Dowex 50W-4X (cationic) resin bead. The spectrum shown in Fig. 1 was obtained by exciting a single 200-μ-diameter bead, containing adsorbed Tb(III), with the 488-nm line of a Spectra-Physics argonion laser, Model 165. The apparatus for performing this study has been described previously. Light from the laser is directed and focused to a spot size of approximately 1 mm diameter. The bead, sealed inside a glass x-ray capillary tube, is placed at this location, and light scattered or emitted from the bead is gathered by a lens normal to the direction of the laser beam and directed into the monochromator of a Ramanor Hg.2S Raman Spectrophotometer, Jobin-Yvon, Instruments SA. This spectrophotometer is equipped with a Nicolet Model 1174 Multichannel Analyzer for signal averaging. The resultant emission spectral data are computer processed as described earlier.