7-Dimethylamino-4-hydroxy-3-methylcumarin, ein neuer, von 429 nm bis 466 nm abstimmbarer Laserfarbstoff
7-Dimethylamino-4-hydroxy-3-methylcoumarin, a new laser dye, tunable from 429 nm to 466 nm
7-Dimethylamino-4-hydroxy-3-methylcoumarin is a useful laser dye in aqueous and alcoholic solutions with a lasing maximum at 434 nm. In acidified solutions its longwave absorption band at 356 nm disappears due to protonation of the dimethylamino group, the fluorescence, however, not being quenched entirely: With increasing acidity its maximum is shifted continuously towards 457 nm, thus providing a simple method for tuning the lasing frequency. Such acid induced bathochromic emission shifts are also found with 7-aminolepidone (“carbostyril 124”), 7-methoxylepidone, 7-ethoxy-4-methylcoumarin and with Eastman Kodak coumarin 102 and are interpreted in terms of concurring ground state N-versus excited state O-protonation.
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