Temperature dependence of charge conversion during NV-center relaxometry

TL;DR

This study investigates how temperature affects charge conversion in NV-center relaxometry, finding that while T1 times decrease with temperature, charge conversion remains unaffected, simplifying temperature-dependent measurements.

Contribution

It provides the first detailed analysis of temperature effects on charge conversion during NV-center relaxometry, clarifying its impact on T1 measurements.

Findings

T1 time decreases with increasing temperature.

Charge conversion is unaffected by temperature changes.

Results simplify temperature-dependent relaxometry analysis.

Abstract

Temperature-dependent nitrogen-vacancy (NV)-center relaxometry is an established tool to characterize paramagnetic molecules near to 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.