Calculation of .pi..pi.* excited state conformations and vibronic structure of retinal and related molecules

1974 ◽  
Vol 96 (18) ◽  
pp. 5677-5689 ◽  
Author(s):  
A. Warshel ◽  
M. Karplus
Keyword(s):  
Excited State ◽  
Vibronic Structure

scholarly journals Excited-State Distortions of Cyclometalated Ir(III) Complexes Determined from the Vibronic Structure in Luminescence Spectra

2007 ◽  
Vol 111 (17) ◽  
pp. 3256-3262 ◽  
Author(s):  
Xianghuai Wang ◽  
Jian Li ◽  
Mark E. Thompson ◽  
Jeffrey I. Zink
Keyword(s):  
Excited State ◽  
Luminescence Spectra ◽  
Vibronic Structure

The electronic absorption spectra of NH 2 and ND 2

1959 ◽  
Vol 251 (1002) ◽  
pp. 553-602 ◽  
Keyword(s):  
Excited State ◽  
Bond Length ◽  
Absorption Spectra ◽  
Flash Photolysis ◽  
Electronic Absorption Spectra ◽  
Interaction Constant ◽  
Bending Vibration ◽  
Vibronic Structure ◽  
Linear Configuration ◽  
Centrifugal Distortion Constants

The absorption spectra of <super>14</super>NH 2 , <super>15</super>NH 2 and <super>14</super>ND 2 have been photographed in the region 3900 to 8300 A with a 21 ft. concave grating spectrograph. The radicals are produced by the flash photolysis of <super>14</super>NH 3 , <super>15</super>NH 3 and <super>14</super>ND 3 respectively. A detailed study of the <super>14</super>NH 2 - <super>15</super>NH 2 isotope shifts suggests that the molecule has a linear configuration in the excited state and that the spectrum consists of a long progression of the bending vibration in this state. These conclusions have been confirmed by detailed rotational and vibrational analyses of the 14NH2 and 14ND2 spectra. The spectra consist of type C bands for which the transition moment is perpendicular to the plane of the molecule. For NH2, sixteen bands of the progression (0, v'%, 0) <- (0, 0, 0) have been identified with v'% — 3, 4, ..., 18. In addition four bands of a subsidiary progression (1, v'2, 0) <- (0, 0, 0) have been found; these bands derive most of their intensity from a Fermi-type resonance between (0, v'2) 0) and (1, v2 —4, 0) levels in the excited state. The interaction constant W nl is 72 + 3 cm <super>-1</super>. For ND 2 , fourteen bands of the principal progression (v2 — 5 to 18) and one band of the subsidiary progression have been identified. The upper state vibration frequencies w?' and (i)' are 3325 cm <super>-1</super> and 622 cm <super>-1</super> for NH 2 and 2520 cm <super>-1</super> and 422 cm <super>-1</super> for ND 2 respectively. The bending frequencies are unusually low ; moreover, the anharmonicities of the bending vibration are unusually large and negative (x22—11.4 cm <super>-1</super> for NH 2 and 8.1 cm <super>-1</super> for ND 2 ). The origin of the system lies in the region o f 10000 cm <super>-1</super>. Ground-state rotational term values have been derived from observed com bination differences; values for the rotational constants Aooo, B'ooo and Cooo and for the centrifugal distortion constants D"A, D"b and D"0 have been determined. The bond lengths and bond angles for NH 2 and ND 2 agree and are 1.024 + 0.005 A and 103° 20' + 30' respectively. Small spin splittings have been observed. In the excited state an unusual type of vibronic structure has been found. Successive levels of the bending vibration consist alternately of 27, d , T, ... and ... vibronic sub-levels with large vibronic splittings. The origins of the vibronic sub-bands may be represented by the formula yf = Vq—GK2, where G is ~ 27 cm -1 for NH 2 and ~ 19 cm <super>-1</super> for ND 2 . The rotational levels show both spin and A-type doubling. No simple formula has been found to fit the energies o f the II, A, 0 and -T rotational levels; the 27 levels fit the formula F(N) = 1) — D N2(N + 1)2, though with a negative value for D . By extrapolating the B values for the 27 levels to = 0 we obtain B'00o = 8.7 8 cm <super>-1</super> for NH 2 and 4.4 1 cm<super>-1</super> for ND 2 . These values are consistent with a linear configuration with a bond length of 0.97 5 A. The significance of this short bond length is discussed. An explanation of the complex vibronic structure is given. The two combining states are both derived from an electronic II state which is split by electronic-vibrational coupling for the reasons advanced by Renner. A detailed correlation diagram is given. A quantitative treatment of this effect by Pople & Longuet-Higgins gives good agreement with the experimental data.

scholarly journals Detailed analysis of the vibronic structure of phenetole in its first excited state and ionic ground state

2019 ◽  
Vol 25 (1) ◽  
pp. 142-156 ◽  
Author(s):  
Niklas Helle ◽  
Immo Hintelmann ◽  
Jürgen Grotemeyer
Keyword(s):  
Excited State ◽  
Ground State ◽  
Bending Vibration ◽  
Vibronic Structure ◽  
Td Dft ◽  
First Excited State ◽  
Electronically Excited ◽  
Mati Spectroscopy ◽  
Adiabatic Ionization Energy ◽  
Franck Condon

The vibronic structure of the first electronically excited state S1 and ionic ground state D0 of phenetole has been investigated by means of resonance enhanced multi photon ionization (REMPI) and mass analyzed threshold ionization (MATI) spectroscopy. The vibronic levels were assigned with the aid of quantum chemical calculations at the (TD)DFT level of theory and a multidimensional Franck-Condon approach. The S1 excitation energy of phenetole has been determined to be 36370 ± 4 cm−1 (4.5093 ± 0.0005 eV). The adiabatic ionization energy was determined to be 65665 ± 7 cm−1 (8.1415 ± 0.0008 eV). The vibronic structure has been analyzed whereby the in-plane bending vibration νbend shows high activity in the first excited state but is more pronounced in the ionic ground state. Moreover, a strong Duschinsky rotation effect can be observed for several D0←S1 transitions that causes violations of the Δv = 0 propensity rule.

Renilla Bioluminescence: A Morphologic Approach to the Location of Photocytes

1974 ◽  
Vol 32 ◽  
pp. 208-209
Author(s):  
Ben O. Spurlock ◽  
Milton J. Cormier
Keyword(s):  
Excited State ◽  
Ground State ◽  
Molecular Basis ◽  
Light Emission ◽  
Chemical Basis ◽  
Electronic Excited State ◽  
Colonial Form ◽  
The Common ◽  
Eighteenth And Nineteenth Centuries ◽  
Catalyzed Oxidation

The phenomenon of bioluminescence has fascinated layman and scientist alike for many centuries. During the eighteenth and nineteenth centuries a number of observations were reported on the physiology of bioluminescence in Renilla, the common sea pansy. More recently biochemists have directed their attention to the molecular basis of luminosity in this colonial form. These studies have centered primarily on defining the chemical basis for bioluminescence and its control. It is now established that bioluminescence in Renilla arises due to the luciferase-catalyzed oxidation of luciferin. This results in the creation of a product (oxyluciferin) in an electronic excited state. The transition of oxyluciferin from its excited state to the ground state leads to light emission.

Integration of Core-Edge Spectroscopy Methods for the Study of Polymers

1996 ◽  
Vol 54 ◽  
pp. 154-155
Author(s):  
E. G. Rightor
Keyword(s):  
Excited State ◽  
Polymer Blends ◽  
Gas Phase ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Electronic States ◽  
Core Electron ◽  
Bulk Solids ◽  
Development Application

Core edge spectroscopy methods are versatile tools for investigating a wide variety of materials. They can be used to probe the electronic states of materials in bulk solids, on surfaces, or in the gas phase. This family of methods involves promoting an inner shell (core) electron to an excited state and recording either the primary excitation or secondary decay of the excited state. The techniques are complimentary and have different strengths and limitations for studying challenging aspects of materials. The need to identify components in polymers or polymer blends at high spatial resolution has driven development, application, and integration of results from several of these methods.

Examining the degradation of environmentally-daunting per- and poly-fluoroalkyl substances from a fundamental chemical perspective

2020 ◽  
Vol 22 (31) ◽  
pp. 17659-17667 ◽  
Author(s):  
Antonio H. da S. Filho ◽  
Gabriel L. C. de Souza
Keyword(s):  
Excited State

In this work, ground and excited-state properties were used as descriptors for probing mechanisms as well as to assess potential alternatives for tackling the elimination of per- and poly-fluoroalkyl substances (PFAS).

Dynamic adjustment of emission from both singlets and triplets: the role of excited state conformation relaxation and charge transfer in phenothiazine derivates

2021 ◽  
Author(s):  
Weidong Qiu ◽  
Xinyi Cai ◽  
Mengke Li ◽  
Liangying Wang ◽  
Yanmei He ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Intramolecular Charge Transfer ◽  
Dynamic Adjustment ◽  
Twisted Intramolecular Charge Transfer

Dynamic adjustment of emission behaviours by controlling the extent of twisted intramolecular charge transfer character in excited state.

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