Abstract.
An unexpected blue-fluorescence band (around 420 nm) from both micrometer-sized dried particles and aqueous droplets of riboflavin [7,8-dimethyl-10-(D-1′-ribityl)-isoalloxazine] is observed when the microparticles are irradiated with a pulsed UV (355- or 351-nm) laser. The intensity of the band increases quadratically with input laser energy density (fluence) and is attributable to a one-photon-excited fluorescence of lumichrome (7,8-dimethyl-alloxazine) that is produced by photo-degradation of riboflavin. The well-known greenish-yellow fluorescence band (at 560 nm for dried particles and 535 nm for aqueous droplets) from riboflavin increases sublinearly with UV-laser fluence. With a laser input fluence above 5 J/cm2 the riboflavin fluorescence decays earlier and the lumichrome fluorescence reaches a maximum later than the peak of the input laser pulse. The temporal dynamics of the 420- and 535-nm fluorescence peaks are consistent with a rate-equation simulation of photon-induced conversion of riboflavin to lumichrome and the subsequent fluorescence of lumichrome.
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Received: 28 September 2000 / Revised version: 11 December 2000 / Published online: 21 February 2001
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Pan, YL., Pinnick, R., Hill, S. et al. Dynamics of photon-induced degradation and fluorescence in riboflavin microparticles . Appl Phys B 72, 449–454 (2001). https://doi.org/10.1007/s003400100532
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DOI: https://doi.org/10.1007/s003400100532