[ { "id": "authors:04hdc-3gw52", "collection": "authors", "collection_id": "04hdc-3gw52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120824-135906485", "type": "article", "title": "Theory of a Single Dye Molecule Blinking with a Diffusion-Based Power Law Distribution", "author": [ { "family_name": "Chen", "given_name": "Wei-Chen", "clpid": "Chen-W-C" }, { "family_name": "Marcus", "given_name": "R. A.", "orcid": "0000-0001-6547-1469", "clpid": "Marcus-R-A" } ], "abstract": "In single molecule studies of injection of an electron from a photoexcited dye into a semiconductor nanoparticle or into a film of such nanoparticles, the injection may be into the conduction band or into the band gap, depending on the system. The theory of the process and its return are discussed, in particular when a power law for the waiting time distribution may be expected and what that power might be. To this end a reaction\u2013diffusion equation is set up and solved. When the injection is into the conduction band, a power law is predicted for the return of the electron to the dye cation but not for the injection. After a short time, the law for the waiting time distribution has a power of \u22121. At short times, before the slower return due to an increasing radius is recognized, the power law is \u22121/2. When the injection is into the band gap, a \u22121 power law is predicted for both the injection and the return. Available data are discussed in terms of the theory. A corollary is that single molecule studies for the injection can determine whether the injection is into the band gap or into the conduction band. The theory is tested by single molecule studies of various systems, such as comparing different dye\u2013TiO_2, dye\u2013Al_2O_3, and dye\u2013ZrO_2 systems and comparing specific dye\u2013TiO_2 systems as a function of pH, and dye hole injection into p-type NiO.", "doi": "10.1021/jp303837g", "issn": "1932-7447", "publisher": "American Chemical Society", "publication": "Journal of Physical Chemistry C", "publication_date": "2012-07-26", "series_number": "29", "volume": "116", "issue": "29", "pages": "15782-15789" }, { "id": "authors:pg6mp-efj28", "collection": "authors", "collection_id": "pg6mp-efj28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100928-111337712", "type": "article", "title": "Isotopomer Fractionation in the UV Photolysis of N_2O: 3. 3D Ab Initio Surfaces and Anharmonic Effects", "author": [ { "family_name": "Chen", "given_name": "Wei-Chen", "clpid": "Chen-W-C" }, { "family_name": "Nanbu", "given_name": "Shinkoh", "clpid": "Nanbu-S" }, { "family_name": "Marcus", "given_name": "R. A.", "orcid": "0000-0001-6547-1469", "clpid": "Marcus-R-A" } ], "abstract": "The wavelength-dependent isotopic fractionation of N_2O is calculated, extending our previous work, Parts 1 and 2, in several aspects: (1) the fully three-dimensional ab initio electronic potential and transition dipole moment surfaces of S. Nanbu and M. S. Johnson (J. Chem. Phys. A 2004, 108, 8905) are used to calculate the absorption cross sections, instead of a 2D surface and (2) the vibrational frequencies and wave functions with anharmonicity correction are used for the ground electronic state. The results for the absorption spectrum and for the isotopic fractionation of the different isotopomers are discussed. One difference between experiments measuring the absorption coefficient (von Hessberg et al. Atmos. Chem. Phys. 2004, 4, 1237) and the others that measure instead the photodissociation is also discussed. Experiments on the quantum yield for wavelengths longer than 200 nm (>50000 cm^(\u22121)) would be helpful in treating the observed difference.", "doi": "10.1021/jp101691r", "issn": "1089-5639", "publisher": "American Chemical Society", "publication": "Journal of Physical Chemistry A", "publication_date": "2010-09-16", "series_number": "36", "volume": "114", "issue": "36", "pages": "9700-9708" }, { "id": "authors:60781-19v14", "collection": "authors", "collection_id": "60781-19v14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:CHEjcp06", "type": "article", "title": "On the theory of the reaction rate of vibrationally excited CO molecules with OH radicals", "author": [ { "family_name": "Chen", "given_name": "Wei-Chen", "clpid": "Chen-W-C" }, { "family_name": "Marcus", "given_name": "R. A.", "orcid": "0000-0001-6547-1469", "clpid": "Marcus-R-A" } ], "abstract": "The dependence of the rate of the reaction CO+OH-->H+CO2 on the CO-vibrational excitation is treated here theoretically. Both the Rice-Ramsperger-Kassel-Marcus (RRKM) rate constant kRRKM and a nonstatistical modification knon [W.-C. Chen and R. A. Marcus, J. Chem. Phys. 123, 094307 (2005).] are used in the analysis. The experimentally measured rate constant shows an apparent (large error bars) decrease with increasing CO-vibrational temperature Tv over the range of Tv's studied, 298\u20131800 K. Both kRRKM(Tv) and knon(Tv) show the same trend over the Tv-range studied, but the knon(Tv) vs Tv plot shows a larger effect. The various trends can be understood in simple terms. The calculated rate constant kv decreases with increasing CO vibrational quantum number v, on going from v=0 to v=1, by factors of 1.5 and 3 in the RRKM and nonstatistical calculations, respectively. It then increases when v is increased further. These results can be regarded as a prediction when v state-selected rate constants become available.", "doi": "10.1063/1.2148408", "issn": "0021-9606", "publisher": "Journal of Chemical Physics", "publication": "Journal of Chemical Physics", "publication_date": "2006-01-14", "series_number": "2", "volume": "124", "issue": "2", "pages": "Art. No. 024306" }, { "id": "authors:3360y-ka816", "collection": "authors", "collection_id": "3360y-ka816", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:CHEjcp05", "type": "article", "title": "On the theory of the CO+OH reaction, including H and C kinetic isotope effects", "author": [ { "family_name": "Chen", "given_name": "Wei-Chen", "clpid": "Chen-W-C" }, { "family_name": "Marcus", "given_name": "R. A.", "orcid": "0000-0001-6547-1469", "clpid": "Marcus-R-A" } ], "abstract": "The effect of pressure, temperature, H/D isotopes, and C isotopes on the kinetics of the OH+CO reaction are investigated using Rice-Ramsperger-Kassel-Marcus theory. Pressure effects are treated with a step-ladder plus steady-state model and tunneling effects are included. New features include a treatment of the C isotope effect and a proposed nonstatistical effect in the reaction. The latter was prompted by existing kinetic results and molecular-beam data of Simons and co-workers [J. Phys. Chem. A 102, 9559 (1998); J. Chem. Phys. 112, 4557 (2000); 113, 3173 (2000)] on incomplete intramolecular energy transfer to the highest vibrational frequency mode in HOCO*. In treating the many kinetic properties two small customary vertical adjustments of the barriers of the two transition states were made. The resulting calculations show reasonable agreement with the experimental data on (1) the pressure and temperature dependence of the H/D effect, (2) the pressure-dependent 12C/13C isotope effect, (3) the strong non-Arrhenius behavior observed at low temperatures, (4) the high-temperature data, and (5) the pressure dependence of rate constants in various bath gases. The kinetic carbon isotopic effect is usually less than 10 per mil. A striking consequence of the nonstatistical assumption is the removal of a major discrepancy in a plot of the kOH+CO/kOD+CO ratio versus pressure. A prediction is made for the temperature dependence of the OD+CO reaction in the low-pressure limit at low temperatures.", "doi": "10.1063/1.2031208", "issn": "0021-9606", "publisher": "Journal of Chemical Physics", "publication": "Journal of Chemical Physics", "publication_date": "2005-09-01", "series_number": "9", "volume": "123", "issue": "9", "pages": "Art. No. 094307" }, { "id": "authors:vr00n-7dd42", "collection": "authors", "collection_id": "vr00n-7dd42", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:GAOjcp02b", "type": "article", "title": "A theoretical study of ozone isotopic effects using a modified ab initio potential energy surface", "author": [ { "family_name": "Gao", "given_name": "Yi Qin", "clpid": "Gao-Y-Q" }, { "family_name": "Chen", "given_name": "Wei-Chen", "clpid": "Chen-W-C" }, { "family_name": "Marcus", "given_name": "R. A.", "orcid": "0000-0001-6547-1469", "clpid": "Marcus-R-A" } ], "abstract": "A modified ab initio potential energy surface (PES) is used for calculations of ozone recombination and isotopic exchange rate constants. The calculated low-pressure isotopic effects on the ozone formation reaction are consistent with the experimental results and with the theoretical results obtained earlier [J. Chem. Phys. 116, 137 (2002)]. They are thereby relatively insensitive to the properties of these PES. The topics discussed include the dependence of the calculated low-pressure recombination rate constant on the hindered-rotor PES, the role of the asymmetry of the potential for a general X + YZ reaction (Y[not-equal]Z), and the partitioning to form each of the two recombination products: XYZ and XZY.", "doi": "10.1063/1.1488577", "issn": "0021-9606", "publisher": "Journal of Chemical Physics", "publication": "Journal of Chemical Physics", "publication_date": "2002-07-22", "series_number": "4", "volume": "117", "issue": "4", "pages": "1536-1543" }, { "id": "authors:1hkhk-c5a29", "collection": "authors", "collection_id": "1hkhk-c5a29", "cite_using_url": "https://resolver.caltech.edu/CaltechCSTR:1984.5140-tr-84", "type": "monograph", "title": "Hierarchy of Graph Isomorphism Testing", "author": [ { "family_name": "Chen", "given_name": "Wen-Chi", "clpid": "Chen-W-C" } ], "abstract": "No Abstract.", "doi": "10.7907/1hkhk-c5a29", "publisher": "California Institute of Technology", "publication_date": "1984-01-01" } ]