title: High sensitivity gas spectroscopy of porous, highly scattering solids.
abstract: We present minimalistic and cost-efficient instrumentation employing tunable diode laser gas spectroscopy for the characterization of porous and highly scattering solids. The sensitivity reaches 3 x 10(-6) (absorption fraction), and the improvement with respect to previous work in this field is a factor of 10. We also provide the first characterization of the interference phenomenon encountered in high-resolution spectroscopy of turbid samples. Revealing that severe optical interference originates from the samples, we discuss important implications for system design. In addition, we introduce tracking coils and sample rotation as new and efficient tools for interference suppression. The great value of the approach is illustrated in an application addressing structural properties of pharmaceutical materials.
authors.affiliation: Department of Physics, Lund University, SE-221 00 Lund, Sweden. tomas.svensson@fysik.lth.se
authors.forename: Tomas
authors.initials: T
authors.lastname: Svensson
authors.forename: Mats
authors.initials: M
authors.lastname: Andersson
authors.forename: Lars
authors.initials: L
authors.lastname: Rippe
authors.forename: Jonas
authors.initials: J
authors.lastname: Johansson
authors.forename: Staffan
authors.initials: S
authors.lastname: Folestad
authors.forename: Stefan
authors.initials: S
authors.lastname: Andersson-Engels
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005740:Gases / Q000032:analysis* / Q000737:chemistry*; D008027:Light; D008029:Lighting / Q000295:instrumentation*; D009391:Nephelometry and Turbidimetry / Q000295:instrumentation*; D016062:Porosity; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation*
chemical_list: D005740:Gases