Laser two-photon ionization of organic molecules in dielectric liquids

Siomos, K.; Kourouklis, G. A.; Christophorou, Loucas G.

doi:10.1016/0009-2614(81)85066-x

Cited by 41 publications

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References 20 publications

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“…The threshold for photoionization in solution is considerably lower than the ionization potential in the gas phase due to the polarization energy of the positive ion and the electron affinity of the solvent (1 0); differences are -1-3 eV for aromatic molecules (10)(11)(12)(13). Thus, UV-vis lasers such as a nitrogen (1)(2)(3)(5)(6)(7)(8), excimer (4), or dye (3,8,12,13) laser should be able to ionize most aromatic molecules by two-photon processes.…”

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confidence: 98%

“…Thus, UV-vis lasers such as a nitrogen (1-3,5-8), excimer (4), or dye (3,8,12,13) laser should be able to ionize most aromatic molecules by two-photon processes. With the use of dye lasers, the two-photon ionization spectra (wavelength dependence of the photoionization signal at a constant photon flux of the laser pulse) were obtained for 9-methylanthracene (8), pyrene (121, fluoranthene (13), and N,N,N',"-tetramethyl-p-phenylenediamine (13,14). The results show that the spectrum has structure (8,12,13) and the signal tends to be larger for a shorter wavelength (8,(12)(13)(14).…”

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confidence: 99%

“…With the use of dye lasers, the two-photon ionization spectra (wavelength dependence of the photoionization signal at a constant photon flux of the laser pulse) were obtained for 9-methylanthracene (8), pyrene (121, fluoranthene (13), and N,N,N',"-tetramethyl-p-phenylenediamine (13,14). The results show that the spectrum has structure (8,12,13) and the signal tends to be larger for a shorter wavelength (8,(12)(13)(14). Since two-photon ionization is more efficient for molecules with larger molar absorptivities from the ground to the first excited states (5,7), wavelength dependence will be valuable in choosing an optimal wavelength for the twophoton ionization detection with the highest signal-to-noise (S/N) ratio.…”

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Laser two-photon ionization spectrometry of perylene and naphthacene in hexane

Yamada¹,

Sato²,

Kawazumi³

et al. 1987

Anal. Chem.

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The two-photon Ionization spectra of perylene and naphthacene In hexane have been measured with tunable dye lasers. They have shown structure, which can be correlated with the onephoton absorption spectra. The signal-to-noise (S/N) ratio has been evaluated as functlons of the excitatlon wavelength and the laser pulse energy, and the detection limit depended on the excitation wavelength, the laser pulse energy, and the molar absorptivity. The lowest detection limits ( S I N = 3) of perylene and naphthacene were 50 pg/mL at 383 nm and 20 pg/mL at 407 nm, respectlvely; these dye laser resuits were superior to those obtained by nitrogen-laser excitation. Table I. Lasers Used in Two-Photon Ionization Experiments wavelength, nm dye solvent 337a 360-376 PBD ethanol/toluene, 50/50 ethanol/toluene, 50/50 p-dioxane 374-394 BBQ 396-412 DPS 412-424 POPOP p-dioxane 418-426 Bis-MSB p-dioxane 426-448 C-440 ethanol 444-472 (2-460 ethanol Nitrogen laser.Laser two-photon ionization in solution is a sensitive technique for detection of polynuclear aromatic hydrocarbons (1-8), drugs (3), quinones (5, 7), and vitamins (6). Experimental conditions such as laser power, bias voltage, irradiation position, and electrode configuration have to be optimized (9), and the design of a photoionization cell is very important for sensitive detection of the photoionization signal (1,2,4,5, 7, 8).The threshold for photoionization in solution is considerably lower than the ionization potential in the gas phase due to the polarization energy of the positive ion and the electron affinity of the solvent (1 0); differences are -1-3 eV for aromatic molecules (10-13). Thus, UV-vis lasers such as a nitrogen (1-3,5-8), excimer (4), or dye (3,8,12,13) laser should be able to ionize most aromatic molecules by two-photon processes. With the use of dye lasers, the two-photon ionization spectra (wavelength dependence of the photoionization signal at a constant photon flux of the laser pulse) were obtained for 9-methylanthracene (8), pyrene (121, fluoranthene (13), and N,N,N',"-tetramethyl-p-phenylenediamine (13,14). The results show that the spectrum has structure (8,12,13) and the signal tends to be larger for a shorter wavelength (8,(12)(13)(14). Since two-photon ionization is more efficient for molecules with larger molar absorptivities from the ground to the first excited states (5,7), wavelength dependence will be valuable in choosing an optimal wavelength for the twophoton ionization detection with the highest signal-to-noise

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Laser two-photon ionization spectrometry of perylene and naphthacene in hexane

Yamada¹,

Sato²,

Kawazumi³

et al. 1987

Anal. Chem.

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“…Siomos et al8,9 measured the two-photon ionization current as a function of the excitation wavelength for some aromatic molecules in n-pentane with the use of tunable dye lasers. Voigtman and Winefordner2 used dye lasers for the detection of a few drugs; the detection limit (S/ N=3) of danthron was 4 ng/ ml at 430 nm.…”

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Two-Photon Ionization Detection of Anthracene Derivatives and Dyes with Tunable Dye Laser Excitation

1987

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Tunable dye lasers have been successfully applied to the two-photon ionization spectrometry of seven anthracene derivatives and five dyes in hexane. The sensitivity depended on the excitation wavelength as well as the molar absorptivity. Detection limits for anthracene, 2-methylanthracene and 1,6-diphenylhexatriene were as low as 20 pg/ml (1 x 10-10 M). The detectability by the dye laser excitation was compared with that by the nitrogen laser excitation.

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“…Hov.ever, little attention has been given to similar processes in the liquid phase. In this paper we report and discuss results obtained with a conductivity technique [1,2] on (1) the photoionization of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) in liquid hydrocarbons, (2) autoio lizing states of fluoranthene in liquid n-pentane, and (3) the effect of coherent versus resonant (stepwise) two-photon excitation in the photoionization process in solutions.…”

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confidence: 99%

Laser two-photon ionization and autoionization spectroscopy of molecules in the liquid phase

Siomos¹,

Kourouklis²,

Christophorou³

1983

Conference on Lasers and Electro-Optics

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The observation of autoionizing states of molecules in the liquid phase together with one-and two-photon ionization threshold measurements obtained using a laser conductivity technique are reported. Coherent versus resonant (st^pwise) two-photon excitation in the photcionization process in solutions is discussed. ' Resea ;h sponsored by the Office of Health and Environmental Research, U.S. Department of Energy, under contract jV-7405-eng-26 with the Union CarbirV Corporation.

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Laser two-photon ionization of organic molecules in dielectric liquids

Cited by 41 publications

References 20 publications

Laser two-photon ionization spectrometry of perylene and naphthacene in hexane

Laser two-photon ionization spectrometry of perylene and naphthacene in hexane

Two-Photon Ionization Detection of Anthracene Derivatives and Dyes with Tunable Dye Laser Excitation

Laser two-photon ionization and autoionization spectroscopy of molecules in the liquid phase

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