Spectroscopic signatures of proton transfer dynamics in the water dimer cation

Using full dimensional EOM-IP-CCSD/aug-cc-pVTZ potential energy surfaces, the photoelectron spectrum, vibrational structure, and ionization dynamics of the water dimer radical cation, (H2O)+2, were computed. We also report an experimental photoelectron spectrum which is derived from photoionization efficiency measurements and compares favorably with the theoretical spectrum. The vibrational structure is also compared with the recent experimental work of Gardenier et al. [J. Phys. Chem. A 113, 4772 (2009)] and the recent theoretical calculations by Cheng et al. [J. Phys. Chem. A 113 13779 (2009)]. A reduced dimensionality nuclear Hamiltonian was used to compute the ionization dynamics for both the ground state and first excited state of the cation. The dynamics show markedly different behavior and spectroscopic signatures depending on which state of the cation is accessed by the ionization. Ionization to the ground-state cation surface induces a hydrogen transfer which is complete within 50 femtoseconds, whereas ionization to the first excited state results in a much slower process

The effect of microhydration on ionization energies of thymine

A combined theoretical and experimental study of the effect of microhydration on ionization energies (IEs) of thymine is presented. The experimental IEs are derived from photoionization efficiency curves recorded using tunable synchrotron VUV radiation. The onsets of the PIE curves are 8.85+-0.05, 8.60+-0.05, 8.55+-0.05, and 8.40+-0.05 eV for thymine, thymine mono-, di-, and tri-hydrates, respectively. The computed (EOM-IP-CCSD/cc-pVTZ) AIEs are 8.90, 8.51, 8.52, and 8.35 eV for thymine and the lowest isomers of thymine mono-, di-, and tri-hydrates. Due to large structural relaxation, the Franck-Condon factors for the 0<-- 0 transitions are very small shifting the apparent PIE onsets to higher energies. Microsolvation strongly affects IEs of thymine -- addition of each water molecule reduces the first vertical IE by 0.10-0.15 eV. The adiabatic IE decreases even more (up to 0.4 eV). The magnitude of the effect varies for different ionized states and for different isomers. For the ionized states that are localized on thymine the dominant contribution to the IE reduction is the electrostatic interaction between the delocalized positive charge on thymine and the dipole moment of the water molecule

Spectroscopic signatures of proton transfer dynamics in the water dimer cation

Using full dimensional EOM-IP-CCSD/aug-cc-pVTZ potential energy surfaces, the photoelectron spectrum, vibrational structure, and ionization dynamics of the water dimer radical cation, (H2O)+2, were computed. We also report an experimental photoelectron spectrum which is derived from photoionization efficiency measurements and compares favorably with the theoretical spectrum. The vibrational structure is also compared with the recent experimental work of Gardenier et al. [J. Phys. Chem. A 113, 4772 (2009)] and the recent theoretical calculations by Cheng et al. [J. Phys. Chem. A 113 13779 (2009)]. A reduced dimensionality nuclear Hamiltonian was used to compute the ionization dynamics for both the ground state and first excited state of the cation. The dynamics show markedly different behavior and spectroscopic signatures depending on which state of the cation is accessed by the ionization. Ionization to the ground-state cation surface induces a hydrogen transfer which is complete within 50 femtoseconds, whereas ionization to the first excited state results in a much slower process

Spectroscopic signatures of proton transfer dynamics in the water dimer cation

Using full dimensional EOM-IP-CCSD/aug-cc-pVTZ potential energy surfaces, the photoelectron spectrum, vibrational structure, and ionization dynamics of the water dimer radical cation, (H2O)+2, were computed. We also report an experimental photoelectron spectrum which is derived from photoionization efficiency measurements and compares favorably with the theoretical spectrum. The vibrational structure is also compared with the recent experimental work of Gardenier et al. [J. Phys. Chem. A 113, 4772 (2009)] and the recent theoretical calculations by Cheng et al. [J. Phys. Chem. A 113 13779 (2009)]. A reduced dimensionality nuclear Hamiltonian was used to compute the ionization dynamics for both the ground state and first excited state of the cation. The dynamics show markedly different behavior and spectroscopic signatures depending on which state of the cation is accessed by the ionization. Ionization to the ground-state cation surface induces a hydrogen transfer which is complete within 50 femtoseconds, whereas ionization to the first excited state results in a much slower process

Non-Condon Effects in the One- and Two-Photon Absorption Spectra of the Green Fluorescent Protein

We report calculations of one and two photon absorption (OPA and TPA, respectively) spectra of the green fluorescent protein (GFP) chromophore using the double-harmonic parallel-mode approximation and including explicit dependence of the electronic transition moments on nuclear geometry. The non-Condon effects are found to be more significant for TPA resulting in a different shape of the spectra and a blue shift of 500 cm⁻¹ of the TPA peak absorption relative to OPA. The computed shift is in excellent agreement with the experimentally observed 700 cm⁻¹

Ab initio potential energy and dipole moment surfaces of the F-(H2O) complex

We present full-dimensional, ab initio potential energy and dipole moment surfaces for the F-(H2O) complex. The potential surface is a permutationally invariant fit to 16,114 coupled-cluster single double (triple)/aVTZ energies, while the dipole surface is a covariant fit to 11,395 CCSD(T)/aVTZ dipole moments. Vibrational self-consistent field/vibrational configuration interaction (VSCF/VCI) calculations of energies and the IR-spectrum are presented both for F-(H2O) and for the deuterated analog, F-(D2O). A one-dimensional calculation of the splitting of the ground state, due to equivalent double-well global minima, is also reported

A novel Gaussian Binning (1GB) analysis of vibrational state distributions in highly excited H2O from reactive quenching of OH* by H2

A novel Gaussian Binning (1GB) analysis of vibrational state distributions in highly excited H2O from reactive quenching of OH* by H

The effect of microhydration on ionization energies of thymine

A combined theoretical and experimental study of the effect of microhydration on ionization energies (IEs) of thymine is presented. The experimental IEs are derived from photoionization efficiency curves recorded using tunable synchrotron VUV radiation. The onsets of the PIE curves are 8.85+-0.05, 8.60+-0.05, 8.55+-0.05, and 8.40+-0.05 eV for thymine, thymine mono-, di-, and tri-hydrates, respectively. The computed (EOM-IP-CCSD/cc-pVTZ) AIEs are 8.90, 8.51, 8.52, and 8.35 eV for thymine and the lowest isomers of thymine mono-, di-, and tri-hydrates. Due to large structural relaxation, the Franck-Condon factors for the 0<-- 0 transitions are very small shifting the apparent PIE onsets to higher energies. Microsolvation strongly affects IEs of thymine -- addition of each water molecule reduces the first vertical IE by 0.10-0.15 eV. The adiabatic IE decreases even more (up to 0.4 eV). The magnitude of the effect varies for different ionized states and for different isomers. For the ionized states that are localized on thymine the dominant contribution to the IE reduction is the electrostatic interaction between the delocalized positive charge on thymine and the dipole moment of the water molecule