Affiliation:
1. Research Institute for Marine Geodynamics Japan Agency for Marine−Earth Science and Technology Yokosuka Japan
2. Research Center for Advanced Science and Technology The University of Tokyo Tokyo Japan
3. Department of Earth and Planetary Science, Graduate School of Science Kyushu University Fukuoka Japan
Abstract
AbstractThe intensity ratio (αI) and area ratio (αA) obtained using Raman spectroscopy are used widely to characterize the physical properties of gases, fluids, and solids, but the underlying parameters which affect their precision (
and
) have not been elucidated. We use simulations, experiments, and theoretical analyses to investigate the effects of instrumental performance, analytical conditions, and sample size on
and
. We identified the parameters which strongly influence
: (1) the weaker peak intensity Iw; (2) the ratio of the bandwidth to pixel resolution of the weaker peak Γw/Δxw; (3) the degree of detector saturation; (4)
with readout noise σR, dark noise σD, and shot noise σS; (5) drift; and (6) sample size. Theoretical and simulation results show that, when Γw/Δxw ≪ (Γs/Δxs)/αI, increasing Iw or Γw/Δxw by n times can improve
by a factor of
. Results showed that
is a measure of how much the achievable
in the experiment differs from that under ideal analytical conditions (i.e.,
). When
is not the case (i.e., when Iw is low), reducing σD or σR by decreasing the readout speed, setting a lower charge coupled device (CCD) sensitivity, reducing number of readouts, or narrowing vertical binning width can improve
. We demonstrated that evaluations of
or
based on small sample sizes can engender physically unattainable precision. When the sample size is n = 5, 10, or 20, the average uncertainties of
and
correspond, respectively, to approximately 30%, 20%, and 15%. Giving an accurate and comparable assessment for
and
necessitates the reporting of intensity (in units of electrons), bandwidth, Δx, and the sample size.
Funder
Japan Society for the Promotion of Science
Subject
Spectroscopy,General Materials Science
Cited by
1 articles.
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