Photothermal Spectroscopy for Planetary Sciences: A Characterization of Planetary Materials in the Mid-IR

TL;DR

This paper evaluates the use of Optical PhotoThermal InfraRed (O-PTIR) spectroscopy for analyzing planetary materials, demonstrating its potential for in-situ planetary surface investigations despite some orientation effects.

Contribution

The study provides a new database of O-PTIR measurements on planetary-relevant minerals and compares it with FTIR, highlighting O-PTIR's suitability for planetary material identification.

Findings

O-PTIR shows granular orientation effects similar to other IR techniques.

O-PTIR measurements are largely comparable to FTIR spectroscopy.

O-PTIR is promising for in-situ planetary surface analysis.

Abstract

Understanding of the formation and evolution of the Solar System requires understanding key and common materials found on and in planetary bodies. Mineral mixing and its implications on planetary body formation is a topic of high interest to the planetary science community. Previous work establishes a case for the use of Optical PhotoThermal InfraRed (O-PTIR) in planetary science and introduces and demonstrates the technique's capability to study planetary materials. In this paper, we performed a measurement campaign on granular materials relevant to planetary science, such as minerals found in lunar and martian soils. These laboratory measurements serve to start a database of O-PTIR measurements. We also present FTIR absorption measurements of the materials we observed in O-PTIR for comparison purposes. We find that the O-PTIR technique suffers from granular orientation effects similar to other IR techniques, but in most cases, is is directly comparable to commonly used absorption spectroscopy techniques. We conclude that O-PTIR would be an excellent tool for the purpose of planetary material identification during in-situ investigations on regolith and bedrock surfaces.