Deep-ultraviolet transient grating for characterizing nanoscale thermal, elastic, and interfacial properties in high-bandgap materials

The functional properties of complex or nanostructured materials deviate from bulk, due to the increased influence of surfaces and interfaces [1,2]. Characterizing these properties is crucial to designing new, efficient nanoelectronics, energy materials, and quantum technologies. In this work, we demonstrate a deep-ultraviolet (DUV) transient grating to characterize a more general set of materials at smaller length scales than visible-based methods allow. We generate <200nm ultrafast DUV pulses [3] to a excite a sample in a transient grating modality. A transient grating is created by interfering two beams to form a spatially-modulated pattern on the sample surface [4]. The resultant heating causes thermal expansion which launches acoustic waves into the sample, allowing us to study its elastic and thermal properties. The visible transient grating periodicity is limited by the wavelength of the light; however, by using DUV light, we are able to create a smaller period interference pattern down to a few hundred nanometers [5]. Moreover, the DUV pulses are above the bandgap for many visibly-transparent samples, extending our technique to more materials, including diamond and next-generation battery technologies.

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References:

[1] J. Knobloch et al., ACS Appl. Mater. Interfaces 14, 41316 (2022)

[2] A. Beardo et al., ACS Nano 15 (8), 13019 (2021)

[3] J. Ringling, et al., Opt. Lett. 18 (23), 2035 (1993)

[4] J. Rogers et al., Ann. Rev. Mater. Sci. 30, 117 (2000)

[5] A. Maznev et al., Appl. Phys. Lett 113, 221905 (2018)