Radiative and nonradiative transitions in the first excited singlet state of symmetrical methyl-substituted acetones

Abstract

Nonradiative transitions in the first excited singlet state of perfluorocyclobutanone: Fluorescence decay times and fluorescence excitation spectroscopy Radiative and nonradiative transitions from the first excited singlet state of methylsubstituted naphthalenes Radiative and nonradiative rates of symmetrically substituted, methylated acetones have been measured in the gas phase. Observed radiative lifetimes are compared to calculated radiative lifetimes obtained from the Strickler-Berg (SB) expression. The calculated values are greater by a factor of 8-9, and an empirical procedure by which the true radiative lifetime can be estimated from the SB expression and the geometry-sensitive correction parameter is given. The rates of nonradiative transitions are reduced appreciably by the a, a' substitution of methyl groups to the C-C-CO-C-C skeleton. The steric crowding introduced by methyl group substitution is considered to be responsible for suppressing the vibrational motion of the promoting modes. In most cases, the S 1 ~ T 1 intersystem crossing predominates over the other nonradiative transitions. rocal disperSion, 5000 A blaze). Light emerging from

Crank Angle Resolved HC-Detection Using LIF in the Exhausts of Small Two-Stroke Engines Running at High Engine Speed

“…During the last years there have been LIF applications using 3-pentanone as a dopant [4,12,13]. The absorption spectrum of 3-pentanone is ranging from 220 to 320 nm with a maximum at 280 nm [14]. As can be seen in figure 2, 3-pentanone (diethyl ketone) has an emission spectrum between 330 and 600 nm, with a peak at 430 nm.…”

Investigations of the Influence of Mixture Preparation on Cyclic Variations in a SI-Engine, Using Laser Induced Fluorescence

“…, has an absorption spectrum ranging from 220 nm to 330 nm with a peak at 280 nm. The emission spectrum range is 330 nm to 600 nm with a peak at 430 nm [22]. The fluorescence quantum yield is found to be essentially independent of excitation wavelength [22], measured in a cell where 10.0 torr 3-pentanone was mixed with 2.0 torr O 2 .…”

“…The molar absorption coefficient for 3-pentanone at 248 nm, 5.3 M-1 cm -1 was found in the absorption spectrum [22].…”

Design and Demonstration of a Spark Ignition Engine Operating in a Stratified-EGR Mode

“…The particles were supplied into one of inert gas supply lines to have clear Table 2.3. Since the wavelength of XeCl-excimer laser is 308 nm, the absorption efficiency is not good [15][16], but in this test, the sufficient amount of acetone was supplied through one of inert gas supply lines by Venturi effect and gravity to have enough fluorescence light intensity. Acetone has been used for a tracer for the measurements of planar fuel distributions and the progress of turbulent mixing formation by planar laser-induced fluorescence [15,17].…”