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Handheld 785 nm Raman applications: Cutting edge material ID capabilities in your pocket

May 30, 2022

Article

Handheld 785 nm Raman is a well-established material identification technique, most notably in the pharmaceutical and defense and security markets. Now, new capabilities developed by Metrohm Raman are expected to increase the capabilities of handheld Raman in diverse industries. This article will first cover the instrumentation and then conclude with several new applications for 785 nm Raman spectroscopy.

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Figure 1. Comparison of high (green) and low (grey) SNR in the Raman spectrum. High SNR results in better library matches.

Flexible sampling optionsshort analysis timessmall form-factor, and superior identification capabilities are the best known benefits of 785 nm handheld Raman systems. Let’s dive a bit deeper and check out how low laser powers and resolution contribute to this growing list.

Short analysis times and low laser powers both preserve battery life for a system—a necessity for handheld Raman in field applications. Low laser powers also pose less risk of sample degradation for safer analysis of unknown materials.

MIRA’s (Metrohm Instant Raman Analyzer) unique spectrometer design collects data in very short analysis times with an excellent signal-to-noise ratio (SNR). A comparison of high (green) and low SNR (grey) in Figure 1 illustrates how noise in a low-resolution spectrum can occlude peak resolution. Ultimately, high SNR means more peak information for optimal library matching.

A demonstration of how wavelength, laser power, acquisition time, and SNR are related can be found in Table 1 and Figure 2. Observe that 1064 nm Raman requires 440 mW (vs. 50 mW) and nearly 10x the sample acquisition time to compare with 785 nm Raman. At the same laser power (50 mW), SNR of 1064 nm Raman is nearly seven times lower than that of 785 nm Raman. It is clear that the high SNR resulting from the combination of lower laser power and shorter sample acquisition time makes 785 nm Raman the ideal choice for analysts.