Axially perpendicular offset scheme for obtaining Raman spectra of housed samples in glass bottles with minimized glass-peak background.

An axially perpendicular offset (APO) scheme based on an axially perpendicular geometrical arrangement of laser illumination and photon detection, enabling spatially offset Raman spectroscopy (SORS), is proposed as a versatile tool for the minimization of the glass background in direct measurements of Raman spectra of samples housed in glass bottles. This strategy is based on the possibility of isolating glass photons from sample photons by properly locating a detector beneath the sample-housing bottle, because glass photons are much more localized near the glass wall while sample photons are widely distributed throughout the bottle. In addition, the curved bottom of the glass vial enabling forming the conical photon-detection volume would be further effective in exclusion of the glass photons in the acquisition of sample spectra.

Data on the concentration-dependent score variations and the results of 2D correlation analysis in the measurements of HSO, HNO, and HPO samples.

Data presented here are related to the original paper "Concentration determination of inorganic acids that do not absorb near-infrared (NIR) radiation through recognizing perturbed NIR water bands by them and investigation of accuracy dependency on their acidities" published by same authors. Here, the concentration-dependent score variations and the results of 2D correlation analysis in the measurements of HSO, HNO, and HPO samples are included; while, the same analysis results obtained in the measurement of HCl samples are presented in the main manuscript. In addition, the correlation plots resulted in the measurements of HCl, HSO, HNO, and HPO samples are also separately shown.

Interleaved incremental association Markov blanket as a potential feature selection method for improving accuracy in near-infrared spectroscopic analysis.

The interleaved Incremental Association Markov Blanket (inter-IAMB) is described herein as a feature selection method for the NIR spectroscopic analysis of several samples (diesel, gasoline, and etchant solutions). Although the Markov blanket (MB) has been proven to be the minimal optimal set of features (variables) that does not change the original target distribution, variables selected by the existing IAMB algorithm could be redundant and/or misleading as the IAMB requires an unnecessarily large amount of learning data to identify the MB. Use of the inter-IAMB interleaving the grow phase with the shrink phase to maintain the size of the MB as small as possible by immediately eliminating invalid candidates could overcome this drawback.

Feasibility for non-destructive discrimination of natural and beryllium-diffused sapphires using Raman spectroscopy.

Raman spectroscopy based non-destructive discrimination between natural and beryllium-diffused (Be-diffused) sapphires has been attempted. The initial examination of Raman image acquired on a sapphire revealed that microscopic structural and compositional heterogeneity was apparent in the sample, so acquisition of spectra able to represent a whole body of sapphire rather than a localized area was necessary for a reliable discrimination. For this purpose, a wide area illumination (WAI) scheme (illumination area: 28.

Axially perpendicular offset Raman scheme for reproducible measurement of housed samples in a noncircular container under variation of container orientation.

An axially perpendicular offset (APO) scheme that is able to directly acquire reproducible Raman spectra of samples contained in an oval container under variation of container orientation has been demonstrated. This scheme utilized an axially perpendicular geometry between the laser illumination and the Raman photon detection, namely, irradiation through a sidewall of the container and gathering of the Raman photon just beneath the container. In the case of either backscattering or transmission measurements, Raman sampling volumes for an internal sample vary when the orientation of an oval container changes; therefore, the Raman intensities of acquired spectra are inconsistent.

Use of temperature dependent Raman spectra to improve accuracy for analysis of complex oil-based samples: lube base oils and adulterated olive oils.

A simple and effective strategy to improve accuracy for Raman spectroscopic analysis of complex mixture samples by probing a measurement temperature yielding enhanced spectral selectivity has been demonstrated. For the evaluation, the determination of Kinematic Viscosity at 40 °C (KV@40) of lube base oil (LBO) samples was initially attempted. Partial least squares (PLS) was used to determine the KV@40 using Raman spectra of the samples collected at 8 different temperatures from 20 to 90 °C with 10 °C increments.