Spectral properties of 4-methylumbelliferone in PVA films; long-lived room temperature phosphorescence.

Lee, Bong; Alexander, Emma; Pham, Dan; GagoÅ›, Mariusz; Matwijczuk, A.; Gryczynski, Z.; Gryczynski, I.

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Spectral properties of 4-methylumbelliferone in PVA films; long-lived room temperature phosphorescence.

Lee, Bong; Alexander, Emma; Pham, Dan; GagoÅ›, Mariusz; Matwijczuk, A.; Gryczynski, Z.; Gryczynski, I.

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Publisher

IOP Publishing

Date

12/10/2024

Abstract

We studied absorption and fluorescence as well as room temperature phosphorescence (RTP) of 4-methylumbelliferone (4MU) in poly (vinyl alcohol) (PVA) films. We focused our study on the long-wavelength basic form of 4MU with absorption centered at 375 nm. The strong fluorescence with a quantum yield of above 70% appears at ~ 430 nm. The fluorescence anisotropy of 4MU-doped PVA film is high, reaching a value of about 0.3. The emission with gated detection shows a broad phosphorescence spectrum with a peak at ~ 510 nm and a residual delayed fluorescence at 430 nm. The excitation spectra for fluorescence and phosphorescence roughly follows 4MU absorption. The phosphorescence lifetime of 4MU is remarkably long, almost 3 s. 4MU excitation and emission phosphorescence anisotropies are low, very close to zero.