# Measurement of Dipole Moments and Lifetimes of Triplet States of Fluorenone and Its Derivatives by Time Resolved Microwave Dielectric Absorption.

15 Apr 1998-Journal of the Physical Society of Japan (THE PHYSICAL SOCIETY OF JAPAN)-Vol. 67, Iss: 4, pp 1220-1225

TL;DR: In this paper, the authors used microwave dielectric absorption to study the excited triplet states formed by the laser flash photolysis and reported the triplet state lifetime and dipole moments of fluorenone and its derivatives.

Abstract: The technique of time resolved microwave dielectric absorption has been used to study the excited triplet states formed by the laser flash photolysis. The details of the experimental method and apparatus are discussed. The triplet state lifetimes and triplet state dipole moments of fluorenone and its derivatives are reported. The triplet state lifetime of fluorenone agrees with that obtained by optical absorption. The lifetime measurements with argon purging and with air equilibrated solution confirm the formation of triplet states. A marked increase in the triplet state dipole moment of fluorenone and its derivatives is observed and implies that their lowest triplet state is of (π, π * ) in nature.

##### Citations

More filters

••

05 May 2012TL;DR: In this article, a 2D finite difference time domain (FDTD) was used to evaluate the forward problem and the inverse problem was solved via a Bayesian approach via a posterior distribution over the model parameters such as complex permittivity.

Abstract: : The motivation of this work is to quantify the degradation of aging electrical cables. The dielectric material parameter of insulation can be correlated with degradation. In this paper, the forward problem is posed as a microwave nondestructive evaluation (NDE) problem. A 2D finite difference time domain (FDTD) was used to evaluate the forward problem. The inverse problem is solved via a Bayesian approach. The Bayesian formulation describes the solution as a posterior distribution over the model parameters such as complex permittivity. Since there is no analytical solution for the posterior distribution, the Markov Chain Monte Carlo (MCMC) method is employed to numerically solve for it. The Metropolis-Hasting algorithm is used in particular. Results for computational experiments are demonstrated to show feasibility of this approach.

1 citations

### Cites background from "Measurement of Dipole Moments and L..."

...Time-Resolved Microwave Dielectric Absorption (TRMDA) enables the measurement of the evanescent electrical field leaking from the probe into the cable insulation by using cavity resonator [2]....

[...]

17 Oct 2011

TL;DR: In this paper, a stochastic inversion technique based on the Metropolis-Hasting algorithm was applied to the problem of quantitative nondestructive evaluation (QNDE) of material aging parameters.

Abstract: : The quantitative nondestructive evaluation (QNDE) of material aging parameters continues to be a very challenging problem. In our approach, we formulated a forward problem arising in specific micro guided wave test. A stochastic inversion technique based on the Metropolis-Hasting algorithm was applied to the problem. The feasibility and validity of the approach was demonstrated through computational experiments.

### Cites background from "Measurement of Dipole Moments and L..."

...Time-Resolved Microwave Dielectric Absorption (TRMDA) enables to measure evanescent electrical field leaking from the probe into the cable insulation by using cavity resonator [2]....

[...]

##### References

More filters

••

TL;DR: In this paper, the dipole moments of the lowest triplet states of a number of aromatic compounds (mostly ketones) have been measured in benzene solution at room temperature, and it was found that the triplet state is of a transstructure.

Abstract: Time-resolved changes in microwave dielectric absorption have been used to study transients formed by laser flash photolysis. Details of the method and apparatus are given. Applications both to the measurements of the dipole moments of transients and to decay kinetics are given. The dipole moments of the lowest triplet states of a number of aromatic compounds (mostly ketones) have been measured in benzene solution at room temperature. States of n..pi..* character generally possess smaller dipole moments than the corresponding ground states while states of ..pi pi..* character (for example, fluorenone) have larger values than the ground state. The triplets of 4-(dimethylamino)benzaldehyde and 4,4'-bis(dimethylamino)benzophenone have rather high values of dipole moment (10.5 and 8.4 D, respectively) showing their charge-transfer character. The triplet state of benzil was found to have zero or near-zero dipole moment, thus confirming that the triplet state is of a transstructure. 7 figures, 1 table.

68 citations

••

TL;DR: In this paper, the Stark effect on the rotational lines of the 1+0 band of the 3A2-1A1 transition of formaldehyde has been studied using field strengths up to 25 ǫkV/cm.

Abstract: The Stark effect on the rotational lines of the 1+–0 band of the 3A2–1A1 (π* ← n) transition of formaldehyde has been studied using field strengths up to 25 kV/cm. Measurements of the Stark splitti...

58 citations

••

TL;DR: In this article, microwave measurements on suspensions of these dye-coated particles have shown large absorption signals when the suspension is irradiated with pulses of 532 nm light from a laser, attributed to mobile charge carriers injected into the TiO2 from the excited singlet state of the dye.

Abstract: The fluorescence of rose bengal is quenched with 96% efficiency when this dye is adsorbed on TiO2 particles. Microwave measurements on suspensions of these dye-coated particles have shown large absorption signals when the suspension is irradiated with pulses of 532 nm light from a laser. The microwave absorption is attributed to mobile charge carriers injected into the TiO2 from the excited singlet state of the dye. The observed rise time of the signal indicates no intermediate surface state of greater than 2 ns lifetime. Various characteristics of the observed signals are compared with those from TiO2 single crystals.

48 citations