A fast time-resolved infrared spectroscopic investigation into the nature of the lowest excited state and excimer formation in PtII diimine cyanides

2002 ◽  
pp. 2857-2861 ◽  
Author(s):  
Marina K. Kuimova ◽  
Michael Ya. Mel'nikov ◽  
Julia A. Weinstein ◽  
Michael W. George
Keyword(s):  
Excited State ◽  
Spectroscopic Investigation ◽  
Fast Time ◽  
Time Resolved ◽  
Infrared Spectroscopic ◽  
Excimer Formation

Picosecond time-resolved infrared spectroscopic investigation of excited state dynamics in a Ptii diimine chromophore

2002 ◽  
pp. 382-383 ◽  
Author(s):  
Julia A. Weinstein ◽  
David C. Grills ◽  
Michael Towrie ◽  
Pavel Matousek ◽  
Anthony W. Parker ◽  
...  
Keyword(s):  
Excited State ◽  
Spectroscopic Investigation ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Infrared Spectroscopic

scholarly journals Triplet energies and excimer formation in meta - and para -linked carbazolebiphenyl matrix materials

2015 ◽  
Vol 373 (2044) ◽  
pp. 20140446 ◽  
Author(s):  
Sergey A. Bagnich ◽  
Alexander Rudnick ◽  
Pamela Schroegel ◽  
Peter Strohriegl ◽  
Anna Köhler
Keyword(s):  
Excited State ◽  
Triplet State ◽  
Spectroscopic Investigation ◽  
Triplet Excited State ◽  
Conjugation Length ◽  
Triplet Energy ◽  
Excimer Formation

We present a spectroscopic investigation on the effect of changing the position where carbazole is attached to biphenyl in carbazolebiphenyl (CBP) on the triplet state energies and the propensity to excimer formation. For this, two CBP derivatives have been prepared with the carbazole moieties attached at the ( para ) 4- and 4 ′ -positions ( p CBP) and at the ( meta ) 3- and 3 ′ -positions ( m CBP) of the biphenyls. These compounds are compared to analogous m CDBP and p CDBP, i.e. two highly twisted carbazoledimethylbiphenyls, which have a high triplet energy at about 3.0 eV and tend to form triplet excimers in a neat film. This torsion in the structure is associated with localization of the excited state onto the carbazole moieties. We find that in m CBP and p CBP, excimer formation is prevented by localization of the triplet excited state onto the central moiety. As conjugation can continue from the central biphenyls into the nitrogen of the carbazole in the para -connected p CBP, emission involves mainly the benzidine. By contrast, the meta -linkage in m CBP limits conjugation to the central biphenyl. The associated shorter conjugation length is the reason for the higher triplet energy of 2.8 eV in m CBP compared with the 2.65 eV in p CBP.

scholarly journals Excited States and Intermediates by Time-Resolved Infrared Spectroscopy

1999 ◽  
Vol 19 (1-4) ◽  
pp. 245-251 ◽  
Author(s):  
J. J. Turner ◽  
M. W. George ◽  
I. P. Clark ◽  
I. G. Virrels
Keyword(s):  
Infrared Spectroscopy ◽  
Excited State ◽  
Charge Transfer ◽  
Excited States ◽  
Fast Time ◽  
Time Resolved ◽  
Excited Species ◽  
Charge Transfer Transitions ◽  
Time Resolved Infrared Spectroscopy ◽  
Kinetics Of

For coordination compounds containing CO or CN groups, fast time-resolved infrared spectroscopy (TRIR) provides a convenient method of probing excited states and intermediates. TRIR has proved particularly powerful for probing the structure and kinetics of organometallic intermediates. The interpretation is particularly straightforward when combined with IR data from matrix isolation experiments, although there can be some subtle differences. In excited state studies, shifts in ν(CO) and ν(CN) frequencies, from ground to excited state, are sensitive to the changes in electron distribution on excitation, thus allowing the distinction between charge-transfer and non-charge-transfer transitions. Subtle effects on excited state ν(CO) band positions occur with change from fluid to rigid solvent-“infrared rigidochromism”. There is often a change in ν(CO) band width on excitation; this can be interpreted in terms of specific interactions between the excited species and the solvent. This paper presents some of our recent work in this area.

Excited-State Triplet-Triplet Absorption in αNPO

1987 ◽  
Vol 41 (8) ◽  
pp. 1318-1324 ◽  
Author(s):  
A. N. Dharamsi ◽  
A. B. Hassam
Keyword(s):  
Excited State ◽  
Fluorescence Spectra ◽  
Intersystem Crossing ◽  
Absorption And Fluorescence Spectra ◽  
Time Resolved ◽  
Quenching Effect ◽  
Excimer Formation ◽  
Concentration Quenching Effect ◽  
Absorption Measurements ◽  
Triplet Absorption

Time-resolved excited-state triplet-triplet absorption measurements in αNPO solutions were performed. A concentration quenching effect on the excited absorption and fluorescence spectra, due to excimer formation, was seen. A numerical analysis of the results yielded the rate constants for intersystem crossing, triplet quenching by O2, triplet self-quenching, and excimer formation.

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