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Nitrogen-vacancy (NV) centers in diamond are an attractive platform for quantum sensing because they exhibit stable optical and spin properties at room temperature [1, 2]. An NV center consists of a nitrogen atom substituting a carbon atom and a neighbouring vacancy in the diamond lattice [2]. Owing to their environmental sensitivity, high spatial resolution, and excellent biocompatibility, NV centers are promising for high-resolution temperature sensing, particularly where conventional infrared thermography cannot be applied [1–4].
This work employs all-optical thermometry based on temperature-dependent shifts of the optical zero-phonon line (ZPL) [5, 6]. All-optical thermometry using NV centers in single-crystal diamond is investigated from approximately 20 °C to 55 °C. The samples are first characterised by confocal microscopy, followed by temperature-dependent measurements in a flow-cell system that simulates future application conditions. Fluorescence spectra are analysed in terms of ZPL position and amplitude, and their spatial variation is used to investigate temperature gradients within the diamond. This provides the basis for future applications in which the temperature of flowing water may be inferred from the measured temperature distribution. First results demonstrate the potential of all-optical NV thermometry for spatially resolved temperature measurements and the investigation of local thermal processes.
[1] M. W. Doherty et al., Physics Reports, vol. 528, no. 1, 2013.
[2] R. Schirhagl et al., Annual Review of Physical Chemistry, 2014, doi: 10.1146/annurev-physchem-040513-103659.
[3] P. G. Kucsko et al., Nature, vol. 500, pp. 54–58, 2013, doi: 10.1038/nature12373.
[4] P. Neumann et al., Nano Letters, vol. 13, no. 6, pp. 2738–2742, 2013, doi: 10.1021/nl401216y.
[5] M. Fujiwara and Y. Shikano, Nanotechnology, 2021, doi: 10.1088/1361-6528/ac1fb1.
[6] M. Li et al., Advanced Quantum Technologies, vol. 7, no. 3, 2024, doi: 10.1002/qute.202300293.
