Isabel Cardoso Barbosa, Jonas Gutsche, Dennis Lönard, Stefan Dix, Artur Widera

• Temperature-dependent nitrogen-vacancy (NV)-center relaxometry is an established tool to characterize paramagnetic molecules near a sensing diamond, gaining momentum in different fields of science. However, recent results indicate that conversion between NV-center charge states impedes these measurements and influences the results for the \(T_1\) time. While the temperature dependence of NV centers’ \(T_1\) time is well studied, additional contributions from temperature-dependent charge conversion during the dark time may further affect the measurement results. We combine temperature-dependent relaxometry and fluorescence spectroscopy at varying laser powers to unravel the temperature dependence of charge conversion in nanodiamond for biologically relevant temperatures. While we observe a decrease of the \(T_1\) time with increasing temperatures, charge conversion remains unaffected by the temperature change. These results allow the temperature-dependent performance of \(T_1\) relaxometry without further consideration of temperature dependence of charge conversion.