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Singh S, Kawade M, Patwari GN. Dissociative Photoionization of Dimethylpyridines and Trimethylpyridine at 266 nm: Dynamics of Methyl Radical Release. ACS OMEGA 2024; 9:8173-8178. [PMID: 38405504 PMCID: PMC10882603 DOI: 10.1021/acsomega.3c08705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 12/22/2023] [Accepted: 01/23/2024] [Indexed: 02/27/2024]
Abstract
The 266 nm photolysis of various positional isomers of dimethylpyridines and trimethylpyridine was investigated by measuring the translational energy distribution of the methyl radical following {sp2}C-C{sp3} bond dissociation. The observed translational energy distribution is attributed to the dissociative photoionization in the cationic ground state following [1 + 1 + 1] three-photon absorption. The translational energy distribution profiles of the methyl radical were broad with the maximum translation energy in excess of 2 eV, which originates due to the dissociation of {sp2}C-C{sp3} bond ortho to the N atom in the ring. The dynamics of {sp2}C-C{sp3} bond dissociation in the cationic ground state of methylpyridines is marginally dependent on the number and position of the methyl groups; similar to xylenes, however, it is site-selective with the preferential cleavage of C-C bond in the ortho position to the pyridinic nitrogen atom, which is attributed to the relative stability of the resulting radical cation.
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Affiliation(s)
- Sumitra Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076 , India
| | - Monali Kawade
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076 , India
| | - G Naresh Patwari
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076 , India
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Ban L, Tang H, Yoder BL, Signorell R. Time-dependent photoemission from droplets: influence of size and charge on the photophysics near the surface. Faraday Discuss 2022; 236:461-484. [PMID: 35507329 PMCID: PMC9408814 DOI: 10.1039/d1fd00108f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Photoemission from submicrometer droplets containing a mixture of dioctyl phthalate and dioctyl sebacate was investigated by femtosecond and nanosecond photoionization. Photoelectron spectra recorded after ionization with single 4.7 eV femtosecond or nanosecond laser pulses showed marked differences between the two cases. These differences were attributed to ionization of long-lived states which only occurred within the duration of the nanosecond pulse. The tentative assignment of the long-lived states to dioctyl phthalate triplet states is discussed. A nanosecond–femtosecond pump–probe scheme using 4.7 eV (pump) and 3.1 eV (probe) pulses was used to investigate the decay dynamics of these long-lived states. The dynamics showed an accelerated decay rate at higher dioctyl phthalate concentrations. Furthermore, the dependence of the decay dynamics on droplet size and charge was investigated. The decay of the long-lived states was found to be faster in smaller droplets as well as in neutral droplets compared with both positively and negatively charged droplets. Possible mechanisms to explain these observations and the dominance of contributions from the droplets surface are discussed. Time-resolved photoemission spectroscopy is used to study the photophysics of droplets containing dioctyl phthalate. Long-lived excited states survive longer at lower phthalate concentrations, and in larger or electrically charged droplets.![]()
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Affiliation(s)
- Loren Ban
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog Weg 2, CH-8093 Zürich, Switzerland.
| | - Hanchao Tang
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog Weg 2, CH-8093 Zürich, Switzerland.
| | - Bruce L Yoder
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog Weg 2, CH-8093 Zürich, Switzerland.
| | - Ruth Signorell
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog Weg 2, CH-8093 Zürich, Switzerland.
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Bejoy NB, Kawade M, Singh S, Patwari GN. Dynamics of Methyl Radical Formation Following 266 nm Dissociative Photoionization of Xylenes and Mesitylene. J Phys Chem A 2022; 126:1960-1965. [PMID: 35294201 DOI: 10.1021/acs.jpca.1c10885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The 266 nm dissociative photoionization of three xylene isomers and mesitylene leading to the formation of methyl radical was examined. The total translational energy distribution profiles [P(ET)] for the methyl radical were almost identical for all of the three isomers of xylene and mesitylene, while a substantial difference was observed for the corresponding P(ET) profile of the co-fragment produced by loss of one methyl group in m-xylene. This observation is attributed to the formation of the methyl radical from alternate channels induced by the probe. The P(ET) profiles were rationalized based on the dissociation of {sp2}C-C{sp3} bond in the cationic state, wherein the {sp2}C-C{sp3} bond dissociation energy is substantially lower relative to the neutral ground state. The dissociation in the cationic state follows a resonant three-photon absorption process, resulting in a maximum translational energy of about 1.6-1.8 eV for the photofragments in the center-of-mass frame. Fitting of the P(ET) profiles to empirical function reveals that the dynamics of {sp2}C-C{sp3} bond dissociation is insensitive to the position of substitution but marginally dependent on the number of methyl groups.
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Affiliation(s)
- Namitha Brijit Bejoy
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Monali Kawade
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sumitra Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - G Naresh Patwari
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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Ban L, Gartmann TE, Yoder BL, Signorell R. Low-Energy Electron Escape from Liquid Interfaces: Charge and Quantum Effects. PHYSICAL REVIEW LETTERS 2020; 124:013402. [PMID: 31976689 DOI: 10.1103/physrevlett.124.013402] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Indexed: 05/27/2023]
Abstract
The high surface sensitivity and controlled surface charge state of submicron sized droplets is exploited to study low-energy electron transport through liquid interfaces using photoelectron imaging. Already a few charges on a droplet are found to modify the photoelectron images significantly. For narrow escape barriers, the comparison with an electron scattering model reveals pronounced quantum effects in the form of above-barrier reflections at electron kinetic energies below about 1 eV. The observed susceptibility to the characteristics of the electron escape barrier might provide access to these properties for liquid interfaces, which are generally difficult to investigate.
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Affiliation(s)
- Loren Ban
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog Weg 2, CH-8093 Zürich, Switzerland
| | - Thomas E Gartmann
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog Weg 2, CH-8093 Zürich, Switzerland
| | - Bruce L Yoder
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog Weg 2, CH-8093 Zürich, Switzerland
| | - R Signorell
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog Weg 2, CH-8093 Zürich, Switzerland
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Okamoto K, Kozawa T, Saeki A, Yoshida Y, Tagawa S. Subpicosecond pulse radiolysis in liquid methyl-substituted benzene derivatives. Radiat Phys Chem Oxf Engl 1993 2007. [DOI: 10.1016/j.radphyschem.2006.06.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Saigusa H, Morohoshi M, Tsuchiya S. Excimer and Exciplex Formation in van der Waals Dimers of Toluene and Benzene. J Phys Chem A 2001. [DOI: 10.1021/jp010910i] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hiroyuki Saigusa
- Department of Environmental Sciences, Faculty of Science, and the Graduate School of Integrated Science, Yokohama City University, Yokohama 236-0027, Japan
| | - Mika Morohoshi
- Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, Tokyo 112-8681, Japan
| | - Soji Tsuchiya
- Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, Tokyo 112-8681, Japan
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Absolute cross-sections for the nonresonant multi-photon ionization of toluene and xylene in the gas phase. Chem Phys 2001. [DOI: 10.1016/s0301-0104(01)00273-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Ogawa T, Ogawa T, Nakashima K. Ionization of Aniline in Nonpolar Hydrocarbon Solvents as Studied by Two-Photon Ionization Spectra. J Phys Chem A 1998. [DOI: 10.1021/jp982220t] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Teiichiro Ogawa
- Department of Molecular and Material Sciences, Kyushu University, Kasuga-shi, Fukuoka 816, Japan
| | - Takashi Ogawa
- Department of Molecular and Material Sciences, Kyushu University, Kasuga-shi, Fukuoka 816, Japan
| | - Keiji Nakashima
- Department of Material Engineering, Kouchi Institute of Technology, Mononobe, Nangoku-shi, Kouchi 783, Japan
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Abstract
Nonresonant two-photon electronic spectroscopy of polyatomic molecules is reviewed for the period since 1979. Emphasis is placed on studies that expose patterns in the two-photon fluorescence (also ionization, optoacoustic) excitation spectra of aromatic hydrocarbons and the effect of vibrations and substitution, particularly within the framework of pseudoparity rules. A section is devoted to biological molecules and the emerging use of two-photon-induced fluorescence anisotropy. Relevant theoretical results are discussed, with emphasis on quantum chemical predictions of vibronic coupling and substituent effects on two-photon absorptivity and tensor properties of individual molecules. This chapter includes higher-order spectroscopy, and a limited number of three- and four-photon studies are discussed.
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Affiliation(s)
- P R Callis
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA.
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11
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Zhang G, Thomas JK. Energy Transfer via Ionic Processes in Polymer Films Irradiated by 0.4 MeV Electrons. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp961074t] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Guohong Zhang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - J. Kerry Thomas
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
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12
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Waldman A, Ruhman S. A femtosecond time-resolved transient bleach study of the benzene excimer. Chem Phys Lett 1993. [DOI: 10.1016/0009-2614(93)85704-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kajii Y, Suzuki T, Takatori Y, Shibuya K, Obi K. Photodissociation of Highly-Excited Triplet State of Benzophenone Studied by a Time-Resolved Thermal Lensing Technique. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1992. [DOI: 10.1246/bcsj.65.1349] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Comparison of UV—visible and UV—IR two-color multiphoton ionization of benzo[a]pyrene in n-heptane: photocurrent investigations. J Photochem Photobiol A Chem 1991. [DOI: 10.1016/1010-6030(91)85103-n] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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15
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Picosecond photolysis of azo compounds in liquid alkanes: germinate recombination kinetics for polyatomic free radical pairs. Chem Phys Lett 1991. [DOI: 10.1016/0009-2614(91)85045-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Fluhler EN, Hurley JK, Kochevar IE. Laser intensity and wavelength dependence of Rose-Bengal-photosensitized inhibition of red blood cell acetylcholinesterase. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 990:269-75. [PMID: 2923906 DOI: 10.1016/s0304-4165(89)80044-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The intensity and wavelength-dependence of Rose-Bengal-mediated photoinhibition of red blood cell acetylcholinesterase has been studied. Irradiation of dye-membrane suspensions with 308 nm laser excitation resulted in enzyme inhibition almost 50% greater than that obtained with 514 nm laser excitation. Sodium azide and argon purging greatly decreased the photosensitized enzyme inhibition at both wavelengths. Although Rose Bengal photosensitized enzyme inhibition more efficiently upon excitation into Sn (308 nm) than into S1 (514 nm), Stern-Volmer analysis of sodium azide quenching data gave similar quenching efficiencies at both wavelengths. Irradiation of dye-membrane suspensions with increasing intensities (Nd:YAG, 532 nm, 40 ps pulse duration) resulted in a decrease in enzyme inhibition. Saturation of the Rose Bengal fluorescence intensity and light transmission occurred with nearly the same intensity-dependence, suggesting that ground-state depletion occurs at the higher intensities. Our results demonstrate that excitation of a sensitizer into higher-lying excited singlet states can result in enhanced sensitizing efficiency. However, attempts to populate such states in Rose Bengal by sequential two-photon absorption using high intensities resulted only in ground-state depletion.
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Affiliation(s)
- E N Fluhler
- Department of Dermatology, Massachusetts General Hospital, Boston 02114
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Chen CH, McCann MP. Measurements of two‐photon absorption cross sections for liquid benzene and methyl benzenes. J Chem Phys 1988. [DOI: 10.1063/1.453781] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Faidas H, Siomos K. Multiphoton ionization studies of benzene in tetramethylsilane and n‐pentane solutions. J Chem Phys 1987. [DOI: 10.1063/1.453677] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Yamada S, Yoshida S, Kawazumi H, Nagamura T, Ogawa T. Fast conductivity signals produced by pulsed laser photoionization of pyrene in non-polar hydrocarbon solvents. Chem Phys Lett 1985. [DOI: 10.1016/0009-2614(85)80243-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Kenney-Wallace GA, Quitevis EL, Templeton EFG. Ultrafast laser spectroscopy: A probe of the photodynamics of chemical intermediates. ACTA ACUST UNITED AC 1985. [DOI: 10.1007/bf03055536] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Whetten RL, Grubb SG, Otis CE, Albrecht AC, Grant ER. Higher excited states of benzene: Polarized ultraviolet two‐photon absorption spectroscopy. J Chem Phys 1985. [DOI: 10.1063/1.448484] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Time-resolved multiphoton ionization in the organic condensed phase: Picosecond conformational dynamics of cis-stilbene and tetraphenylethylene. Chem Phys Lett 1984. [DOI: 10.1016/0009-2614(84)85326-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Prock A, Das KN, Melman P. Extrinsic photoconduction with reduced image forces. J Chem Phys 1983. [DOI: 10.1063/1.446276] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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