Flashlamp-Excited Dye Lasers

Everett, Patrick N.

doi:10.1007/978-3-540-47385-5_6

Cited by 12 publications

(1 citation statement)

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“…Besides an increased photostability a reduced triplet state lifetime leads to a decreased triplet-triplet absorption which can be decisive for laser efficiency [11][12][13][14][15][16]. Molecular parameters important for dye laser action for a number of rhodamine dyes were measured in our group by using a time resolved laser-scanning-microscopy technique [17,18].…”

Section: Introductionmentioning

confidence: 99%

Singlet molecular oxygen photosensitized by Rhodamine dyes: correlation with photophysical properties of the sensitizers

Stracke

Heupel

Thiel

1999

Journal of Photochemistry and Photobiology A: Chemistry

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By measuring its IR phosphorescence the formation of singlet molecular oxygen 1 O 2 photosensitized by rhodamine dyes is directly proved. The 1 O 2 formation rate is compared with that expected from the low probability (≈1%) of intersystem crossing of the photosensitizers. The quantum yield for triplet population and the triplet lifetime of the investigated dyes is measured by using a laser-scanning-microscopy technique. The influence of quenching agents (nitrobenzene and COT) is discussed. It results that the formation of 1 O 2 can be prevented effectively by quenching of the S 1 or T state of the photosensitizer. The influence of the molecular ground-state oxygen 3 O 2 concentration [ 3 O 2 ] is investigated. The presence of the paramagnetic 3 O 2 leads to an increased S 1 →T intersystem crossing rate of the photosensitizers and therefore to a reinforced formation of singlet molecular oxygen. It is found for rhodamine 6G as well as for rose bengal that in air-saturated acetonitrile nearly the half of the excited dye triplets are quenched by molecular oxygen. The 1 O 2 concentration can be significantly reduced by decreasing the 3 O 2 concentration below its air saturated level.

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