Laser two-photon ionization spectroscopy of molecules in liquids

Siomos, K.; Christophorou, L. G.

doi:10.1016/0009-2614(80)80237-5

Cited by 50 publications

(22 citation statements)

References 15 publications

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“…20 The present results in aerated solvents indicate that the ionization threshold of pyrene in hexane and cyclohexane should lie between 5.18 and 4.66 eV, and that in iso-octane should lie between 4.66 and 4.14 eV. There are two reported values: 6.02 eV in neo-pentane, 19 and 4.80 -4.79 eV in pentane 21 and hexane. 22 The above results seem to support the smaller value.…”

Section: Ionization Thresholdmentioning

confidence: 58%

Two-Photon Ionization Efficiency of Pyrene and Several Aromatic Compounds at 240, 266 and 299 nm and Its Analytical Applications

2000

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The laser two-photon ionization of pyrene and several aromatic compounds was investigated in three hydrocarbon solvents by exciting them at 240, 266 and 299 nm using the fourth-harmonic of a Nd:YAG laser and a Raman shifter. The photoionization process consisted of one-photon and two-photon processes at 240 and 266 nm without deaeration, but was a two-photon process even at 240 nm when oxygen was removed. The two-photon ionization efficiency of pyrene was larger upon excitation at shorter wavelengths and in solvents with a larger electron mobility. However, because of large blank signals of the solvents, the detection limits of these molecules were poorer than those previously reported.

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Section: Ionization Thresholdmentioning

confidence: 58%

Two-Photon Ionization Efficiency of Pyrene and Several Aromatic Compounds at 240, 266 and 299 nm and Its Analytical Applications

2000

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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.…”

mentioning

confidence: 99%

“…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. 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).…”

mentioning

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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confidence: 99%

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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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“…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.…”

mentioning

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 spectroscopy of molecules in liquids

Cited by 50 publications

References 15 publications

Two-Photon Ionization Efficiency of Pyrene and Several Aromatic Compounds at 240, 266 and 299 nm and Its Analytical Applications

Two-Photon Ionization Efficiency of Pyrene and Several Aromatic Compounds at 240, 266 and 299 nm and Its Analytical Applications

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

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

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