Spectra of zinc tetrabenzporphyrin in n-octane

1976 ◽  
Vol 29 (5) ◽  
pp. 933 ◽  
Author(s):  
PE Fielding ◽  
AWH Mau
Keyword(s):  
Excited States ◽  
Energy Surface ◽  
Soret Band ◽  
Relative Magnitude ◽  
Host Matrix ◽  
Solvent Interaction ◽  
Band Emission ◽  
Hot Band ◽  
Franck Condon ◽  
Surface Minima

A detailed spectroscopic study of zinc tetrabenzporphyrin in n-octane reveals the following: (i) the relative magnitude of solute-solvent interaction in the ground and excited states increases in the order T1 < S0 < S1 < S2. (ii) The potential energy surface minima of the ground and excited states are very similar within the framework of the Franck-Condon principle. (iii) The absence of any hot-band emission from the Q band (S1) and any emission from the Soret band (S2) indicates that significant amounts of energy degrade to the lowest vibrational level of S1. (iv) An earlier report on monomer phosphorescence is mainly due to aggregation. Selective narrow-band excitation is shown to be a useful technique to unravel complex spectra of porphyrins in Shpolskii-type matrices. Accurate measurements can be made of the energies for electronic transitions between the ground and excited states of molecules isolated in the various sites of the host matrix. The intensity ratios for electronic and vibronic bands can also be determined.

Second order nonlinear optical properties of corroles: experimental and theoretical investigations

2012 ◽  
Vol 16 (12) ◽  
pp. 1276-1284 ◽  
Author(s):  
Xiao Ying ◽  
Xiao-Yan Long ◽  
Mian HR Mahmood ◽  
Quan-Yuan Hu ◽  
Hai-Yang Liu ◽  
...  
Keyword(s):  
Excited States ◽  
Rayleigh Scattering ◽  
Soret Band ◽  
Incident Wavelength ◽  
Maximum Value ◽  
Theoretical Investigations ◽  
Scattering Technique ◽  
Donor Acceptor ◽  
Neglect Of Differential Overlap ◽  
Good Agreement

The first hyperpolarizabilities, βHRS, of corrole derivatives have been measured by using Hyper–Rayleigh Scattering technique. The results showed that βHRS of corroles could be greatly enhanced by modifying its periphery with donor–acceptor groups. Maximum value reaches 354 × 10-30 esu at an incident wavelength of 1500 nm. βHRS of investigated corroles were also calculated with the Zerner's intermediate neglect of differential overlap/configuration interaction/sum-over-states method. The calculated and experimental results are in good agreement and conclude that βHRS arises mainly from the charge transfer along molecule's non-symmetrical axis and strong coupling between two different excited states of the Soret band.

Fluorescence from the A 2Σ+ state suggests a non-Franck–Condon N2O+• vibrational state population after keV collisional activation with helium

2011 ◽  
Vol 89 (3) ◽  
pp. 303-309 ◽  
Author(s):  
Yawei Lin ◽  
Paul M. Mayer
Keyword(s):  
Vibrational State ◽  
Reference Data ◽  
Laboratory Frame ◽  
Translational Energy ◽  
Parent Molecule ◽  
Charge Coupled Device ◽  
Band Emission ◽  
Ccd Detector ◽  
Franck Condon ◽  
Curve Crossing

A commercial analytical mass spectrometer coupled with a spectrograph and charge-coupled device (CCD) detector was used to obtain the collision-induced emission (CIE) spectra (190–1020 nm) from ion–molecule collisions between N2O+• and He at laboratory frame collision energies of 4–8 keV. The observed emissions were from the A 2Σ+ → X 2Π+ system of N2O+•, excited fragments of the parent molecule, and the target gas. The relative emission intensities of the N2O+• ions and their fragments were independent of the ion translational energy within the 4–8 keV range, confirming the curve-crossing mechanism for translational-to-internal energy transfer in this system. Band emission intensities of [Formula: see text] and [Formula: see text] relative to the [Formula: see text] band within the N2O+• (A → X) system have been measured and compared with reference data. The results indicated that the collisionally excited ion has a decidedly non-Franck–Condon vibrational state distribution.

Interaction of UV radiation with DNA helices

2009 ◽  
Vol 81 (9) ◽  
pp. 1635-1644 ◽  
Author(s):  
Dimitra Markovitsi
Keyword(s):  
Energy Transfer ◽  
Excited States ◽  
Flash Photolysis ◽  
Photon Absorption ◽  
Base Pairs ◽  
Relaxation Energy ◽  
Double Helices ◽  
Fluorescence Upconversion ◽  
Theoretical Investigations ◽  
Franck Condon

Recent experimental and theoretical investigations dealing with model DNA double helices, composed of either adenine–thymine (A–T) or guanine–cytosine (G–C) base pairs, and G quadruplexes shed some light on the excited states populated by photon absorption and their relaxation, energy transfer among bases, and one-photon ionization. These studies revealed that the Franck–Condon excited states of DNA helices cannot be considered as the sum of their monomeric constituents because electronic coupling induces delocalization of the excitation over a few bases. Energy transfer takes place via intraband scattering in less than 100 fs. The fluorescence lifetimes of DNA helices detected by fluorescence upconversion and corresponding mainly to ππ* transitions are longer than that of an equimolar mixture of nucleotides; the only exception was observed for alternating G–C polymers. Moreover, nanosecond flash photolysis experiments showed that organization of bases within single and double helices may lead to a lowering of their ionization potential. Finally, the first determination regarding the time-scale needed for the formation of T dimers, the (6–4) adducts, was determined for the single strand (dT)20.

RESONANCES IN H+HLi SCATTERING FOR NONZERO TOTAL ANGULAR MOMENTUM (J > 0): A TIME-DEPENDENT WAVE PACKET APPROACH

2006 ◽  
Vol 05 (04) ◽  
pp. 871-885 ◽  
Author(s):  
R. PADMANABAN ◽  
S. MAHAPATRA
Keyword(s):  
Angular Momentum ◽  
Wave Packet ◽  
Total Angular Momentum ◽  
Energy Surface ◽  
Chem Phys ◽  
Time Dependent ◽  
Coriolis Coupling ◽  
Initial State ◽  
Sudden Approximation ◽  
Franck Condon

The resonances in H + HLi scattering for nonzero total angular momentum (J > 0) are examined here by a time-dependent wave packet approach employing an ab initio potential energy surface (PES) [Dunne LJ, Murrell JN, Jemmer P, Chem Phys Lett336: 1, 2001] of the system. The resonances are identified by calculating a set of pseudospectra corresponding to the Franck–Condon transition of a hypothetical initial state to the interaction region of the H + HLi PES. The resonances are characterized by calculating their eigenfunctions and linewidth lifetimes. The resonances for J ≠ 0 are discussed in relation to their counterpart for J = 0. The effect of Coriolis coupling on the resonances obtained from the centrifugal sudden approximation for J = 2 and for K = 0,1,2 is examined.

Fluorescence Enhancement of a Microbial Rhodopsin via Electronic Reprogramming

2018 ◽  
Author(s):  
Maria del Carmen Marin ◽  
Damianos Agathangelou ◽  
Yoelvis Orozco-González ◽  
Alessio Valentini ◽  
Yoshitaka Kato ◽  
...  
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Excited States ◽  
Fluorescence Quantum Yield ◽  
Fluorescence Enhancement ◽  
Energy Surface ◽  
Wild Type ◽  
Excited State Lifetime ◽  
State Potential ◽  
Microbial Rhodopsin

The manuscript reports on two mutations of the photo-sensory protein Anabaena Sensory Rhodopsin and how these mutations modify the fluorescence quantum yield with respect to the wild-type protein. Experimental results are presented and explained theoretically on the basis of mixing of the S1 and S2 excited states. This mixing modulated by electrostatic and steric effects, tunes the excited state potential energy surface, and thereby the excited state lifetime and the fluorescence quantum yield.<br>

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