V. Palm et al., LINE-WIDTH STUDY IN FLUORESCENCE EXCITATION-SPECTRA OF SINGLE PENTACENE MOLECULES INTRODUCED AS IMPURITIES IN P-TERPHENYL CRYSTAL, Journal of physical chemistry, 98(9), 1994, pp. 2219-2221
We report results on line widths in the fluorescence excitation spectr
a of single pentacene molecules in p-terphenyl crystal flakes for the
O-1 and O-2 sites at 1.85 K. A setup for the measurement of fluorescen
ce excitation spectra of single impurity molecules with an overall qua
ntum efficiency of about 0.1% has been designed. Spectra obtained with
a signal-to-noise ratio up to 10:1 were recorded at different laser e
xcitation intensities in the range from 1 to 5 mW/cm(2). The line widt
hs measured for different pentacene impurity molecules and extrapolate
d to zero probing intensity show remarkable variation in the range fro
m 5 to 15 MHz. A reason why some lines are narrower than the lifetime-
limited one (8 MHz) is discussed.