PMID- 23757480
OWN - NLM
STAT- MEDLINE
DCOM- 20131119
LR  - 20130618
IS  - 1364-5528 (Electronic)
IS  - 0003-2654 (Linking)
VI  - 138
IP  - 14
DP  - 2013 Jul 21
TI  - Minimising contributions from scattering in infrared spectra by means of an 
      integrating sphere.
PG  - 4191-201
LID - 10.1039/c3an00381g [doi]
AB  - Mid-infrared spectra of biological matter such as tissues or microbial and 
      eukaryotic cells measured in a transmission-type optical setup frequently show 
      strongly distorted line shapes which arise from mixing of absorption and 
      scattering contributions. Scattering-associated distorted line shapes may 
      considerably complicate the analysis and interpretation of the infrared spectra 
      and large efforts have been made to understand the mechanisms of scattering in 
      biological matter and to compensate for spectral alterations caused by 
      scattering. The goals of the present study were two-fold: firstly, to get a 
      deeper understanding of the physics of scattering of biological systems and to 
      explore how physical parameters of the scatterers such as shape, size and 
      refractive index influence the line shape distortions observed. In this context, 
      simulations based on the full Mie scattering formalism for spherical particles 
      were found to be useful in explaining the characteristics of the Mie 
      scatter-associated distortions and yielded a size criterion for the scattering 
      particles similar to the well-known near field criterion. The second objective of 
      the study was to investigate whether alternative optical setups allow 
      minimisation of the effects of scattering. For this purpose, an optical system is 
      proposed which is composed of an integrating sphere unit originally designed for 
      diffuse reflection measurements, an off-axis DLaTGS detector to collect scattered 
      and transmitted light components and a commercial Fourier transform infrared 
      (FTIR) spectrometer. In the context of this study transmission type (tt-) FTIR 
      spectra and spectra acquired by means of the integrating sphere setup (is-FTIR) 
      were acquired from monodisperse poly(methyl) methacrylate (PMMA) microspheres of 
      systematically varying sizes. The tt-FTIR spectral data of different PMMA 
      particles confirmed earlier observations such as the presence of size-dependent 
      oscillating spectral baselines, peak shifts, or derivative-like spectral line 
      shapes. Such effects could be dramatically minimised when is-FTIR spectra were 
      acquired by the integrating sphere unit. Utilisation of an integrating sphere is 
      suggested as a convenient and easy-to use alternative to computer-based methods 
      of scatter correction.
FAU - Dazzi, Alexandre
AU  - Dazzi A
AD  - Laboratoire de Chimie Physique, UMR8000, Universite Paris-Sud 11, 91405 Orsay, 
      France.
FAU - Deniset-Besseau, Ariane
AU  - Deniset-Besseau A
FAU - Lasch, Peter
AU  - Lasch P
LA  - eng
PT  - Journal Article
DEP - 20130612
PL  - England
TA  - Analyst
JT  - The Analyst
JID - 0372652
RN  - 9011-14-7 (Polymethyl Methacrylate)
SB  - IM
MH  - *Algorithms
MH  - Computer Simulation
MH  - Light
MH  - Microspheres
MH  - Polymethyl Methacrylate/*chemistry
MH  - *Scattering, Radiation
MH  - Spectroscopy, Fourier Transform Infrared/*methods
EDAT- 2013/06/13 06:00
MHDA- 2013/11/20 06:00
CRDT- 2013/06/13 06:00
PHST- 2013/06/13 06:00 [entrez]
PHST- 2013/06/13 06:00 [pubmed]
PHST- 2013/11/20 06:00 [medline]
AID - 10.1039/c3an00381g [doi]
PST - ppublish
SO  - Analyst. 2013 Jul 21;138(14):4191-201. doi: 10.1039/c3an00381g. Epub 2013 Jun 12.