Single Argon Research Articles

The Role of Viscosity in Sorption-Effect Chromatography

In sorption-effect chromatography, a band of sample gas is detected when it enters and leaves a chromatographic column by monitoring changes in flow rate. The differential capillary flow meter that has been used to detect the changes caused by gas adsorption also responds to changes composition. In previous work on sorption-effect chromatography, the results obtained when a hydrogen sample gas was Injected Into helium carrier gas were inexplicable. In comparison, it seemed possible to explain results obtained using argon or nitrogen in helium. In the present work, analyses are carried out with and without dead volume between the column and flow meter—with different combinations of packed columns and empty tubing—in order to determine why hydrogen should act differently. A large dead volume between the column and the flow meter splits both the Inexplicable hydrogen peak and also the seemingly explicable single argon peak into two separate peaks. The explanation is that the first peak is due to the sorption effect when gas desorba from the column and the second is used by the changing viscosity in the flow meter as the composition changes.

Isolation of giant DNA fragments from flow‐sorted human chromosomes

We have established a method using a conventional cell sorter equipped with a single argon laser to sort intact human chromosomes that can be used as a source for the production of giant DNA fragments. Various improvements were made to both the equipment and sorting method to enhance the sorting resolution and avoid destruction of chromosomal DNA. Using this improved method chromosomes 21 and 22 were sorted from the B-lymphoblastoid line GM00130B, digested with the rare cutting restriction endonuclease NotI, and analyzed by pulsed field gel electrophoresis followed by Southern hybridization using the Alu repetitive sequence as a probe. More than 25 discrete NotI giant DNA fragments ranging from 50 kb to longer than 2.5 Mb were separated and the size distribution pattern was unique for each chromosome, indicating successful sorting of intact chromosomes. The cumulative size of these Alu-positive NotI DNA fragments were 22.7 Mb and 25.5 Mb for chromosomes 21 and 22, respectively. These values are 47% and 49% of the estimated size of chromosomes 21 (48 Mb) and 22 (52 Mb).

Energy effects in secondary ion emission of implanted and simultaneously sputtered argon

Two states of implanted argon (single atoms and solid argon bubbles) cause splitting in energy distributions of Ar + secondary ions emitted from metal and semiconductor surfaces under Ar + ion bombardment. Steady state conditions of the sputtered surfaces influence the Ar + energy peak position.

Biostimulation of human caecinoma cells with the argon laser: A previously unreported potential iatrogenic effect of lasers

The human squamous carcinoma cell line P3 was subjected to treatment with a single mode argon laser at 514.5 nm. The temperature and energy levels delivered to the target cells were determined by a reproducible method of dosimetry. At energy levels between 860 to 990 J/cm2 and a corresponding temperature of 39 +/- 1 degrees C, a significant delayed stimulation in DNA synthesis was noted after 24 hours, but the cells remained viable. However, at energy levels and temperatures higher or equal to 1100 J/cm2 (41 degrees C), an immediate suppression of DNA synthesis was accompanied by nonviability of the P3 carcinoma cells. These results indicate that the argon laser has potential for selective biostimulation on carcinoma cell duplication at the specific "non-thermal" range of 39 +/- 1 degrees C. Similar effects were not observed when the P3 carcinoma cells were heated to this same temperature using a standard heat bath. This phenomenon appears to represent a previously undescribed potential iatrogenic effect of the monochromatic laser beam in the treatment of cancer.

The effects of argon lasers on human melanoma cells sensitized with rhodamine-123 in vitro

A human melanoma cell line, M14, was first exposed to a nontoxic dose of Rhodamine-123 (1 microgram/ml) for one hour, then subjected to a treatment with a single mode argon laser at 514.5 nm. The temperature and energy levels delivered to the target cells were determined by a reproducible method of dosimetry. Cell viability was assessed by the Trypan Blue exclusion test. Cell duplication and DNA synthesis were measured by the incorporation of 3H-thymidine at 6 and 24 hours post-treatment. At energy levels and temperatures higher or equal to 950 J/cm2 (40 degrees C), an immediate suppression of DNA synthesis was accompanied by nonviability of the M14 carcinoma cells. At energy levels between 130-900J/cm2 corresponding to temperatures between 28 to 39 degrees C, both an immediate and delayed inhibition of DNA synthesis was noted but the cells remained viable. The results indicate that Rhodamine-123 at nontoxic doses of 1 microgram/ml enhances the tumoricidal effects of the argon laser at reduced temperatures as low as 40 degrees C. Furthermore, at physiological temperature ranges as low as 28 to 30 degrees C, an immediate inhibition of cell duplication was demonstrated while cell viability was not affected. These observations suggest that Rhodamine-123 can be used effectively as a chemosensitizing agent in the treatment of human tumor cells with the argon laser at 514.5 nm.

Discrimination of viable and non-viable cells using propidium iodide in two color immunofluorescence.

The relative ease with which a flow cytometer can perform simultaneous two color immunofluorescence to examine subpopulations of lymphoid cells has been well documented. Thus, flow cytometers equipped with only a single argon laser can be used to delineate various cell types by exciting both fluorescein- and phycoerythrin-conjugated antibodies to cell surface antigens. One problem that remains, however, is the artifactual staining of dead cells and clumps, which cannot be distinguished from viable cells on the basis of cell surface staining characteristics. We describe a method for simultaneous two color analysis or sorting of viable leukocytes which requires only a single laser. The method utilizes propidium iodide, which stains dead cells and thereby excludes such cells from the analysis. Using this method, as many as four viable cell types have been simultaneously analyzed in a single sample.

Novel technique for isolation of human lung mast cells

A novel technique for isolation of human lung mast cells is developed. Human lung tissue was enzymatically digested and the cells were partially purified by centrifugation on Percoll density gradient. Cells obtained at the Percoll density of 1.05–1.09 g/ml were then subjected to a cell sorter equipped with a single argon laser beam (FACS 440). Using four criteria as density, granularity, size and autofluorescence, four major cell populations were identified. One of the major populations contained 70–95% mast cells with a mean and SE values of 88 ± 11% purity, n = 18 as determined by the measurement of total histamine content, light microscopic observation of stained cells with toluidine blue and estrase, and surface-stained IgE fluorescence antibody. Approximately less than 10% mast cells were identified in the three other major cell populations. Mast cells isolated by FACS were found to be intact, viable ( ⋍ 90%) and functionally normal as determined by the release of histamine evoked after stimulation with ionophone A23187, or challenged with anti-human IgE.

Rhodamine-123 as a new photochemosensitizing agent with the argon laser: "nonthermal" and thermal effects on human squamous carcinoma cells in vitro.

A human squamous carcinoma cell line (P3) was first exposed to a nontoxic dose of Rhodamine-123 (1 microgram/ml for 1 hour), then subjected to treatment with a single mode argon laser at 514.5 nm. The temperature and energy levels delivered to the target cells were determined by a reproducible method of dosimetry. Cell viability was assessed by the trypan blue exclusion test. Cell duplication and DNA synthesis were measured by the incorporation of 3H-thymidine at 6 and 24 hours post-treatment. The results indicate that Rhodamine-123 at nontoxic doses of 1 microgram/ml enhanced the tumoricidal effects of the argon laser at reduced temperatures as low as 40 degrees C. Furthermore, at physiological temperature ranges as low as 28 to 39 degrees C, an immediate and/or delayed inhibition of cell duplication was demonstrated, while cell viability was not affected. These observations, suggest that Rhodamine-123 can be used effectively as a chemosensitizing agent in the treatment of human tumor cells with the argon laser at 514.5 nm. This new technique of tumor cell targeting by Rhodamine sensitization and specific laser treatment may offer real advantages without the extreme photosensitivity associated with hematoporphyrin derivatives.

Origin of the line shapes from intramolecular Penning ionization in benzene/argon clusters

A supersonic beam of benzene (Bz) seeded in argon was ionized by VUV radiation from the Berlin electron storage ring (BESSY). Resonance structures in the photoionization efficiency curves of Bz and Bz⋅Arn (n=1,...,4) are attributed to intramolecular Penning ionization after excitation of argon within a mixed cluster. The dependence of the shapes of the resonance lines on the seed ratio and on the cluster size is reported. It is concluded that formation of large mixed clusters causes broad resonances which are blue shifted relative to the monomer absorption line, whereas the excitation of a single argon atom bound to benzene causes narrow and red shifted lines.

Comparative Efficacy of Continuous and Pulsed Argon Laser Ablation of Human Diseased Ventricle

We compared the tissue lesions obtained in a saline medium using single continuous argon laser discharges with paired sequential continuous laser discharges in nine segments of diseased human ventricle resected from patients with and without ventricular tachycardia (VT) at cardiac surgery. Single continuous argon laser discharges were delivered to separate sites on the endocardial surface of the tissue segments for periods of 10, 20, and 30 seconds at laser beam power of 5 W (group IA) and 8 W (group IIA). Paired sequential argon laser discharges of 5, 10, and 15 seconds in duration were delivered to separate sites at a laser power of 5 W (group IB) and 8 W (group IIB). Gross and microscopic examination of each tissue lesion and its dimensions were performed. Laser irradiation of excised human ventricle resulted in a circular discrete burn at the site of application. Histologic examination showed crater formation due to tissue vaporization with the crater lining consisting of charred tissue and a zone of coagulation necrosis. Analysis of lesion dimensions in groups IA and IIA showed comparable lesion depth and diameter with single continuous and paired sequential laser discharges at energies of 50 J (p greater than .2), 100 J (p greater than .2), and 150 J (p greater than .2). Similarly, lesion depth and diameter were comparable in groups IB and IIB at the same energies. We conclude that paired sequential argon laser discharges may be used to produce comparable tissue lesions to single continuous argon laser discharges in diseased human ventricle.

CARS spectrometer with cw intra‐cavity excitation for high‐resolution Raman spectroscopy

AbstractThe construction of a cw CARS spectrometer is described, consisting of a single mode argon ion ring laser, an intra‐cavity sample cell and a tunable dye laser. The argon laser was first stabilized to an iodine absorption line. From an evaluation of the CARS spectrum of the Q‐branch of the rovibrational band of nitrogen, the vibration‐rotation interaction constant is obtained as αe = 0.0173850 ± 0.0000035 cm−1, in agreement with Bensten's result from the linear Raman spectrum of the total band. Finally, the stabilization of the argon laser to a hyperfine component in the Doppler‐free polarization spectrum of iodine is described.

Flow cytometry: a new method for characterization of differential ingestion, digestion and egestion by suspension feeders

Flow cytometry: a new method for characterization of differential ingestion, digestion and egestion by suspension feeders

Interferometric study of natural convection heat transfer in a horizontal annulus with irregular boundaries

The natural convective heat transfer across an annulus with irregular boundaries was studied using a Mach-Zehnder interferometer. The annulus was formed by an inner hexagonal cylinder and an outer concentric circular cylinder. This configuration models, in two dimensions, a liquid metal fast breeder reactor spent fuel subassembly inside a shipping container. During the test, the annulus was filled with a single gas, either neon, air, argon, krypton, or xenon, at a pressure of about 0.5 MPa. From temperature measurements, both local and mean Nusselt numbers (NuΔ) at the surface of the inner cylinder were evaluated as a function of the Rayleigh number (RaR) and angular location (Δ is the maximum gap width). The data correlation for the mean Nusselt and Rayleigh numbers is given by NuΔ = 0.794RaR0.25. The local heat transfer changes nonmonotonically from the bottom to the top of the hexagonal cylinder. For RaR ≥ 8.15 × 102 the flow in the upper half of the annulus was always unsteady while that in the lower half was steady.

High power second harmonic generation of 257 nm radiation in an external ring cavity

Continuous wave high power frequency doubling of a stabilized, single mode argon ion laser in a resonant external ring cavity is discussed and experimental results are presented. The second harmonic is generated in a Brewster cut ADP crystal which is 90° temperature phase matched. Greater than 80 millwattts of stable, usable radiation at 257 nm is generated. Successful operation of the ring cavity with an internal harmonic beamsplitter to extract the UV radiation is reported.

Ion beam sputter-deposited diamondlike films

A single argon ion beam source was used to sputter deposit carbon films on fused silica, copper and tantalum substrates under conditions of sputter deposition alone and sputter deposition combined with simultaneous argon ion bombardment. Simultaneously deposited and ion bombarded carbon films were prepared under conditions of carbon atom removal to arrival ratios of 0, 0.36, and 0.71. Deposition and etch rates were measured for films on fused silica substrates. Resulting characteristics of the deposited films are: electrical resistivity of ≳1011 Ω cm, densities of 2.1 g/cm3 for sputter-deposited films and 2.2 g/cm3 for simultaneously sputter-deposited and Ar ion-bombarded films. For ∠1700-Å thick films deposited by either process and at 5550 Å wavelength light the reflectance was 0.2, the absorptance was 0.7, the absorption coefficient was 6.7×104 cm−1, and the transmittance was 0.1.

Color center laser pumped with a DCM dye laser

A CW, DCM dye laser has been used to pump a RbCl:Li crystal in a color center laser. The DCM dye laser was pumped by the 488 nm and 514.5 nm lines of an argon ion laser. When used in a broad band configuration the dye laser had a power output in the TEM 00 mode in excess of 600 mW at a wavelength of 655 nm. An output power in excess of 10 mW at 2.73 μm was possible from the RbCl:Li crystal in a Burleigh FCL for an input power of 600 mW at 655 nm. This method of pumping for the RbCl:Li alleviates the need for both argon ion and krypton ion laser pumps for the Burleigh FCL. All three crystals can be pumped to the specification power levels with a single argon ion laser.

The infrared matrix isolation spectra of carbon dioxide. II. Argon matrices: the CO2 monomer bands

Evidence is presented that the cause of the doubling of the infrared bands of CO2 in an argon lattice is the presence of two types of acceptable sites for the CO2 molecule. The nature of these sites is discussed; it is concluded that the sites are double substitutional sites, in which a CO2 molecule occupies the place of two adjacent argon atoms, and single substitution sites, in which the CO2 molecule occupies the place of a single argon atom. A CO2 molecule in a double substitutional site is a more stable situation than a CO2 molecule in a single substitutional site: the former gives a higher v3 and lower v2 frequency than the latter.

Precise measurement and assignment of CW laser emission lines from optically pumped Na<inf>2</inf>and Li<inf>2</inf>molecules

We report the precise wavelength measurement (0.01 Å or 0.03 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) of CW laser emission lines from Li <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and Na <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> molecules, optically pumped by a single frequency argon laser. All 22 lines from Li <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> have been assigned unambiguously. We observed, for the first time in these systems, the existence of pure Raman laser lines (nonresonant pumping and gain without population inversion). Among the 49 lines from Na <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> , 13 could not be assigned, which suggests the possibility of other pumping mechanisms: collision induced transitions or two-step excitation to a higher electronic state.

Sub-Doppler laser spectroscopy of the NaK molecule

Excitation of NaK molecules in a collimated molecular beam by a single mode tunable argon laser with sub-Doppler resolution allows selective population of definite vibrational rotational levels (v′, J′) in the D 1Π-state. The resultant fluorescence consists of a singlet spectrum in the 470–570 nm range and a triplet spectrum in the 625–715 nm range. The analysis of the triplet fluorescence, which consists of discrete lines and of a modulated continuum, allows the determination of the a 3Σ+ potential and yields very precise values for the dissociation energies in the a 3Σ+ and X 1Σ+ states, which are measured as De(3Σ+) =204±4 cm−1 and De(1Σ+) =5269±6 cm−1. For some excitation wavelengths a fluorescence spectrum with discrete lines and with a double-modulated continuum is observed which is assigned to ’’ Condon internal diffraction’’ bands terminating close below and above the dissociation limit of the X 1Σ+ state. Its relevance for the determination of the upper and lower potential curves is discussed.

High resolution laser spectroscopy of Cs2. I. Ground state constants and potential curve

Excitation and fluorescence spectra of the Cs2 molecule were measured with high resolution allowing resolution of the rotational structure. These spectra were studied under excitation by different lines of a single mode argon laser which could be continuously tuned across spectral intervals of about 10 GHz. For excitation in a cesium vapor cell the spectral resolution was only limited by the Doppler width of the absorption lines while in a collimated cesium beam a resolution between 20 and 60 MHz could be achieved. Accurate molecular constants and the RKR potential of the X 1Σ+g ground state are derived from more than 900 fluorescence lines, most of which were precisely measured with a Fabry–Perot interferometer crossed with a monochromator. The dissociation energy of the ground state is deduced from an extrapolation beyond the highest measured level with v″=72, and also from a second laser-excited fluorescence spectrum that appears at the red end of the singlet spectrum and consists of a continuum and a few discrete lines. This spectrum is assigned to transitions terminating in the X 3Σ+u state, which is mainly repulsive. Like the X 1Σ+g state, it too dissociates into two Cs atoms in their 6 2S1/2 ground states.