The quantum yield of a fluorophore is closely linked to the temperature of its surroundings. The objective of this project was to characterize the relative fluorescence quantum yields of several dyes and quantum dots across a wide range of temperatures. Attention was primarily paid to the Rhodamine family of dyes (specifically Rhodamine B, 6G, and 101) and quantum dots that contained an InP core with either a ZnSe or ZnS shell. The dyes were dissolved in an ethylene glycol solvent while the quantum dots were suspended in octadecene. The absorption, fluorescence excitation, and fluorescence emission of these fluorophores were measured at regular intervals from 20 °C to 140 °C and then back down to 20 °C. The results of this project demonstrate that the Rhodamine dyes exhibit thermal quenching to varying degrees depending on molecular structure. For all three dyes the quenching was found to be reversible upon cooling. This contrasts with the quantum dots, whose fluorescence intensity was permanently quenched due to an increase in temperature.

Measuring the temperature-dependent fluorescence of rhodamine dyes and InP-based quantum dots

ACS Spring 2022

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