Related Experiment Video
Updated: Jun 26, 2026

Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
Bandpass effects in time-resolved diffuse spectroscopy
1IIT, CNR-INFM and CNR-IFN, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy. andrea.farina@polimi.it
Abstract:
This paper discusses the spectral distortions occurring when time-resolved spectroscopy of diffusive media is performed illuminating with a wide bandpass. It is shown that the spectral region within the bandpass that exhibits the lowest absorption will dominate the resulting time-resolved curve, leading to significant underestimations of absorption as well as distortions in the spectral shape (including shifts in peak positions). Due to the nonlinear behavior of absorption, this effect becomes even more pronounced when including longer and longer photon path lengths. First, a theoretical treatment of the problem is given, and then the distortion is described by time-resolved reflectance simulations and experimental measurements of lipid and water samples. A spectrally constrained data analysis is proposed that takes into account the spectrum of the light injected into the sample, used to overcome the distortion and improve the accuracy of the estimation of chromophore concentrations from absorption spectra. Measurements on a lipid sample show a reduction of the error from 30% to 6%.
Related Concept Videos
Bandpass Sampling
A bandpass signal has a spectrum with a lower frequency limit, denoted as ω1, and an upper frequency limit, denoted as ω2. The spectrum...
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
Double Resonance Techniques: Overview
Spin decoupling is usually achieved by...
IR Spectrometers
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
UV–Vis Spectroscopy: Beer–Lambert Law

