Chapter 3
Theoretical Models of Light Scattering
and Absorption
Kevin D. Dahm and Donald J. Dahm
Abstract When light interacts with a single particle, there are three possible
outcomes: absorption, scattering, or transmission. In spectroscopy, one measures the
remission from and/or transmission through a macroscopic sample. Such a sample
might contain countless locations at which there is a change in refractive index, each
of which gives rise to scattered light. This fact poses a challenge in building theoretical models applicable to spectroscopy: even if our theoretical understanding of
single interactions is very good, the number of individual interactions is typically too
big to make accounting for all of them realistic. This chapter presents an overview of
modeling strategies that can be of use in near infrared spectroscopy. Recognizing that
no one approach is uniformly applicable, care is taken to call attention to assumptions made in each modeling approach and limitations that are imposed by these
assumptions.
Keywords Absorption · Absorbance · Scattering · Remission · Transmission ·
Diffuse reflectance
This chapter explores the physical behavior of light. When light interacts with a
material, it can:
(1) Continue in the direction it was going, (2) be absorbed by the material, or (3) be
diverted in a different direction and continue traveling along a new path. It is common,
and broadly accurate, to refer to these three possible outcomes as (1) “transmission,”
(2) “absorption,” and (3) “scattering.”
This chapter examines several theoretical approaches to understanding and
modeling these interactions. No one of these approaches can be considered definitive
or universally applicable for spectroscopy. Care is taken to state the assumptions that
underlie each approach, and the limitations that result from these assumptions.
K. D. Dahm (B)
Rowan University College of Engineering, Glassboro, USA
e-mail: dahm@rowan.edu
D. J. Dahm
Retired, North Palm Beach, USA
© Springer Nature Singapore Pte Ltd. 2021
Y. Ozaki et al. (eds.), Near-Infrared Spectroscopy,
https://doi.org/10.1007/978-981-15-8648-4_3
37
Theoretical Models of Light Scattering
and Absorption
Kevin D. Dahm and Donald J. Dahm
Abstract When light interacts with a single particle, there are three possible
outcomes: absorption, scattering, or transmission. In spectroscopy, one measures the
remission from and/or transmission through a macroscopic sample. Such a sample
might contain countless locations at which there is a change in refractive index, each
of which gives rise to scattered light. This fact poses a challenge in building theoretical models applicable to spectroscopy: even if our theoretical understanding of
single interactions is very good, the number of individual interactions is typically too
big to make accounting for all of them realistic. This chapter presents an overview of
modeling strategies that can be of use in near infrared spectroscopy. Recognizing that
no one approach is uniformly applicable, care is taken to call attention to assumptions made in each modeling approach and limitations that are imposed by these
assumptions.
Keywords Absorption · Absorbance · Scattering · Remission · Transmission ·
Diffuse reflectance
This chapter explores the physical behavior of light. When light interacts with a
material, it can:
(1) Continue in the direction it was going, (2) be absorbed by the material, or (3) be
diverted in a different direction and continue traveling along a new path. It is common,
and broadly accurate, to refer to these three possible outcomes as (1) “transmission,”
(2) “absorption,” and (3) “scattering.”
This chapter examines several theoretical approaches to understanding and
modeling these interactions. No one of these approaches can be considered definitive
or universally applicable for spectroscopy. Care is taken to state the assumptions that
underlie each approach, and the limitations that result from these assumptions.
K. D. Dahm (B)
Rowan University College of Engineering, Glassboro, USA
e-mail: dahm@rowan.edu
D. J. Dahm
Retired, North Palm Beach, USA
© Springer Nature Singapore Pte Ltd. 2021
Y. Ozaki et al. (eds.), Near-Infrared Spectroscopy,
https://doi.org/10.1007/978-981-15-8648-4_3
37