Fluorescence decay of laser-excited organic molecules

Lessing, H.E.; Lippert, E.; Rapp, W.

doi:10.1016/0009-2614(70)80300-1

Cited by 43 publications

(13 citation statements)

References 4 publications

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“…The generation of such a short pulse in Pheo a, in which the fluorescence lifetime is expected to be approximately 5 nsec (11,12), is shown in Fig. 4 (8) showed that, at high excitation intensities, a characteristic nonexponential decay and considerable decay time shortening for fluorescence occurs in laserexcited organic molecules due to stimulated emission, and they pointed out that, if induced emission is not accounted for, severe errors in the determination of the fluorescence decay time constants may result. The fact that the photon fluxes required to initiate laser action are of the same order as those used in the picosecond fluorescence lifetime studies suggests that the possibility of stimulated emission should be considered in the interpretation of the fluorescence data.…”

Section: Resultsmentioning

confidence: 99%

Chlorophyll lasers: Stimulated light emission by chlorophylls and Mg-free chlorophyll derivatives

Hindman

Kugel

Svirmickas

et al. 1977

Proc. Natl. Acad. Sci. U.S.A.

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Stimulated emission and lasing have been demonstrated for chlorophyll a, chlorophyll b, and bacteriochlorophyll a as well as for the Mg-free chlorophyll derivatives pheophytin a and methyl pheophorbide a. Population inversion was obtained by optically pumping with an N2 laser. For the three chlorophylls, lasing was observed for only the (0,0) vibronic region of the SI -_ So fluorescence band. In contrast, lasing was observed for both the (0,0) and (0,1) vibronic regions of the SI SO fluorescence band of pheophytin a and methyl pheophorbide a. Differences between the lasing behavior of the chlorophylls and the Mg-free derivatives probably reflect differences in aggregation behavior. Laser pulses of duration shorter than the fluorescence lifetimes were generated. This result suggests that stimulated emission must be considered in the interpretation of fluorescence lifetime data for in vitro and in vivo chlorophyll-containing systems.Chlorophylls (Chi) are the principal photoreceptors for photosynthesis in green plants, algae, and bacteria as well as the electron donors in the primary event of photosynthesis. It is therefore not surprising that keen interest continues in the excited electronic states of the chlorophylls and their Mg-free derivatives. The chlorophylls are intensely fluorescent, and consideration of the lifetimes of the first excited singlet states (SI) and the fluorescence quantum yields suggested that the chlorophylls should have the ability to function as dye lasers. In addition to the usefulness of ChI dye lasers in photosynthesis experiments, lasing of the chlorophylls could be expected to yield interesting information about the properties of their SI electronic states. This has proved to be the case. Chlorophyll a (Chi a), chlorophyll b (Chi b), bacteriochlorophyll a (Bchl a), and the Mg-free derivatives pheophytin a (Pheo a) and methyl pheophorbide a (MePheo a) all have excellent lasing properties, some of which we describe in this paper. The Mg-free derivatives exhibit an interesting, although not unprecedented, dependence of the lasing frequency on the concentration. The characteristics of the laser pulse raise some interesting questions, which we discuss below, about the properties of high densities of excited ChI electronic states such as may be produced in in vwo picosecond irradiations by high photon fluxes. EXPERIMENTAL A 1-MW N2 laser (Molectron model UV 1000) with output at 337.1 nm was used as an optical pump to produce population inversion. This N2 laser was also used as an excitation source for the fluorescence spectra. The experimental configuration was similar to that employed by Sorokin and Lankard (1) in the first demonstration of lasing from an organic compound, aluminum phthalocyanine chloride, in solution when pumped by a giant pulse ruby laser. The cells used for the lasing and fluorescence studies were stoppered 1-cm-square quartz cuvettes polished on all four sides. The laser cavity was defined by the two surfaces of the cuvette perpendicular to the optical pumpin...

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Section: Resultsmentioning

confidence: 99%

Chlorophyll lasers: Stimulated light emission by chlorophylls and Mg-free chlorophyll derivatives

Hindman

Kugel

Svirmickas

et al. 1977

Proc. Natl. Acad. Sci. U.S.A.

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“…The fluorescence lifetimes of organic laser dyes are typically in the 1-10 nsec range, which can be directly measured [12,13,14] Table 1 and Figure 1. Typical error is ~-10% except for lifetimes shorter than 1 nsec where accurate measurements become difficult.…”

Section: Methodsmentioning

confidence: 99%

Study of excitation transfer in laser dye mixtures by direct measurement of fluorescence lifetime

Lin¹,

Dienes²

1973

Journal of Applied Physics

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“…In the above discussion, the pumping intensity effect (16)(17)(18)(19)(20) represented by the stimulated emission rates (Iea and Ieb) in equation set [lo] was not considered. Since the stimulated emission rate (I, or Ieb) is a function of the excited state population as well, the solution of the equation set [lo], which could only be solved numerically, is very complicated.…”

Section: Effect Of Pumping Intensitymentioning

confidence: 99%

“…As the pumping intensity is increased above the threshold value (W*), stimulated emission will compete with spontaneous emission and radiationless deactivation of species A* and B*, which leads not only to a shortening of the decay time but also to strong non-exponential decay (18). For the purpose of extrapolation to KAsE at the pumping intensity threshold value, KASE(Wth), eq.…”

Section: Effect Of Pumping Intensitymentioning

confidence: 99%

High-resolution amplified spontaneous emission (ASE) gain spectroscopy to study excited state complexation

Yip¹,

Wen²

1991

Can. J. Chem.

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Can. J. Chem. 69, 2142(1991. Weakly bound excited state complexes involving 7-diethylamino-4-methylcoumarin have been studied by ASE gain spectroscopy to explore the applicability of the method for studying excited state complexation. Comparative steady state spectrofluorometric and ASE gain measurements showed that ASE gain measurements are capable of giving information on excited state complexation of the laser dye but with greater ease and frequency resolution.Key words: excited state complex, amplified spontaneous emission, laser gain, ASE gain spectroscopy. [Traduit par la redaction]

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Fluorescence decay of laser-excited organic molecules

Cited by 43 publications

References 4 publications

Chlorophyll lasers: Stimulated light emission by chlorophylls and Mg-free chlorophyll derivatives

Chlorophyll lasers: Stimulated light emission by chlorophylls and Mg-free chlorophyll derivatives

Study of excitation transfer in laser dye mixtures by direct measurement of fluorescence lifetime

High-resolution amplified spontaneous emission (ASE) gain spectroscopy to study excited state complexation

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