Showing papers on "Photoionization mode published in 1981"
TL;DR: In this article, the fluorescence and photoacoustic properties of a windowless flow cell intended for liquid chromatographic applications are compared with respective characteristics of a static cuvette cell and a photoionization mode of operation for the flow cell is exhibited which utilizes the ionization products of two-photon excitation of polynuclear aromatic hydrocarbons in n-alkanes to effect a sensitive detection of those PAHs.
Abstract: The fluorescence and photoacoustic characteristics of a windowless flow cell intended for liquid chromatographic applications are compared with respective characteristics of a static cuvette cell. In addition, a photoionization mode of operation for the flow cell is exhibited which utilizes the ionization products of two-photon excitation of polynuclear aromatic hydrocarbons in n-alkanes to effect a sensitive detection of those PAHs.
74 citations
41 citations
TL;DR: In this article, an accurate treatment of radiative transfer is used to explore the effects of grain scattering properties on the photoionization and photodissociation efficiencies of atomic and molecular constituents in diffuse clouds and to calculate the rates of heat deposition by photoelectric emission from grains.
Abstract: An accurate treatment of radiative transfer is used to explore the effects of grain scattering properties on the photoionization and photodissociation efficiencies of atomic and molecular constituents in diffuse clouds and to calculate the rates of heat deposition by photoelectric emission from grains. The observational data on ionization and dissociation are consistent with, but do not establish, a grain scattering model which is highly anisotropic at short wavelengths.
37 citations
TL;DR: The relative photoionization cross section for Ar2 was measured in the wavelength region 820-860 A with no contribution from direct ionization as discussed by the authors, and the appearance potential of Ar+2 corresponds to 8565 ± 15 A
27 citations
TL;DR: Asymmetry parameters and vibrational intensity ratios for the 2 Π μ ionization of acetylene have been measured with different line sources (Ar II, Ne I, He I, Ne II, He II) as mentioned in this paper.
27 citations
23 citations
Patent•
12 May 1981
TL;DR: A high efficiency photoionization detector using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionisation cross section which closely matches the emission spectrum of xenon gas was presented in this article.
Abstract: A high efficiency photoionization detector using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionization cross section which closely matches the emission spectrum of xenon gas. Imaging proportional counters are also disclosed using the novel photoionization detector of the invention. The compound of greatest interest is TMAE which comprises tetrakis(dimethylamino)ethylene which has a measured ionization potential of 5.36±0.02 eV, and a vapor pressure of 0.35 torr at 20° C.
19 citations
TL;DR: In this article, a broad band pulsed dye laser of 5915 A was used to study the initial electronic state distribution of photon-produced ions and the degree of ionization within the uranium vapor.
Abstract: Multiphoton ionization of uranium atoms followed by laser‐induced fluorescence detection of uranium ions is used to study the initial electronic state distribution of photon‐produced ions and the degree of ionization within the uranium vapor. Our experimental data clearly demonstrate that photoionization of uranium through the 50 701 cm−1 excited even levels using a broad band pulsed dye laser of 5915 A produces roughly 50% ground state ions and 50% metastably excited (289 cm−1) ions. The effective photoionization cross section is about 4.7×10−17 cm2. The subsequent dispersion of UII after photoionization appears to be caused by ambipolar expansion of ions and electrons in the plasma. The gA values for the 4050 and 3859 A transitions of UII are measured to be 0.86×108 and 2.8×108 s−1, respectively.
14 citations
TL;DR: In this paper, the detection of naphthalene molecules at partial pressure of 10-14 Torr in the photoionization volume of a mass spectrometer and with relative concentration in air of 10 -7%, which corresponds to 4 molecules in the ionization volume, is reported.
11 citations
TL;DR: In this paper, the two-step photoionization of Na 2 molecules in a molecular beam has been studied using both a singlemode and a multimode Ar + laser as the ionization light source.
9 citations
TL;DR: The photoionization process for UV-initiated and UV-sustained CO laser operation was investigated by measuring the photoion density produced by a single spark source using charge collection.
Abstract: The photoionization process for UV‐initiated and UV‐sustained CO laser operation was investigated by measuring the photoion density produced by a single spark source using charge collection. C2H4 and NO were studied as potential low‐temperature additives for enhancing photoion production, both of which photoionized by a single‐step process with a conversion efficiency of spark energy into photoionization of about 1%. The photoionization was also found to increase linearly with dissipated spark energy, was independent of the spark circuit parameters, and at constant gas and additive density was also independent of temperature.