Instrumental Aspects of Dynamic Two-Dimensional Infrared Spectroscopy

1993 ◽  
Vol 47 (9) ◽  
pp. 1324-1328 ◽  
Author(s):  
Curtis Marcott ◽  
A. E. Dowrey ◽  
Isao Noda
Keyword(s):  
Ir Spectra ◽  
Two Dimensional ◽  
Time Resolved ◽  
Ir Spectrometry ◽  
2D Ir ◽  
Scanning Interferometer ◽  
Atactic Polystyrene ◽  
Ft Ir ◽  
The Time Domain ◽  
Two Dimensional Infrared Spectroscopy

Dynamic two-dimensional infrared (2D IR) correlation maps are a convenient means of examining the information contained in time-resolved IR spectra. Dynamic 2D IR spectra can be collected with the use of either dispersive or Fourier transform (FT) IR spectrometers. Use of a step-scanning FT-IR spectrometer has advantages over conventional rapid-scan FT-IR spectrometry when one is acquiring time-resolved IR data on time scales faster than about 0.1 s, because the spectral multiplexing is removed from the time domain. Dynamic IR spectra of atactic polystyrene (undergoing a small-amplitude oscillatory strain) collected on both dispersive and FT instrumentation are compared. Although the dispersive approach produces higher signal-to-noise ratios over small spectral regions, the multiplex advantage makes the FT approach attractive when broader spectral coverages are required. The first vibrational circular dichroism (VCD) spectrum [of (–)- α;-pinene] collected on a step-scanning interferometer is also presented.

Two-Dimensional Correlation Analysis of Time-Resolved Step-Scan FT-IR Spectra of a Liquid Crystalline Guest—Host System in an Electric Field

1997 ◽  
Vol 51 (11) ◽  
pp. 1698-1702 ◽  
Author(s):  
Miroslaw A. Czarnecki ◽  
Bojidar Jordanov ◽  
Stefano Okretic ◽  
Heinz W. Siesler
Keyword(s):  
Correlation Analysis ◽  
Electric Field ◽  
Ir Spectra ◽  
Relaxation Times ◽  
Hydrocarbon Chain ◽  
Aliphatic Chain ◽  
Two Dimensional ◽  
Time Resolved ◽  
Ft Ir ◽  
Nematic Solvent

The time-resolved step-scan FT-IR spectra of a solution of 2-naphthaldehyde in a nematic solvent were recorded during switching of an electric field. The mesogen of the nematic solvent consisted of a nitrile-substituted bicyclohexyl unit and had a flexible aliphatic chain attached to it. Two-dimensional (2D) correlation analysis of the dynamic spectra was undertaken in order to investigate the details of the molecular orientation and relaxation of the sample under the influence of this electric field. In addition, from the time-resolved spectra the relaxation times of selected functionalities were estimated. The results yield strong evidence that both the nematic solvent and the solute reorient in phase at similar rates. However, the movement of the hydrocarbon chain of the nematic solvent seems to be slightly delayed with respect to the mesogen and the solute. It has been shown that the rigidity of the mesogen plays an important role in the mechanism of the electric-field-induced reorientation of the aliphatic chain.

scholarly journals Two-dimensional infrared spectroscopy of vibrational polaritons

2018 ◽  
Vol 115 (19) ◽  
pp. 4845-4850 ◽  
Author(s):  
Bo Xiang ◽  
Raphael F. Ribeiro ◽  
Adam D. Dunkelberger ◽  
Jiaxi Wang ◽  
Yingmin Li ◽  
...  
Keyword(s):  
Ir Spectra ◽  
Mechanical Model ◽  
Quantum Mechanical ◽  
Two Dimensional ◽  
Coherent Light ◽  
Molecular Systems ◽  
2D Ir ◽  
New Interpretation ◽  
The Impact ◽  
Two Dimensional Infrared Spectroscopy

We report experimental 2D infrared (2D IR) spectra of coherent light–matter excitations––molecular vibrational polaritons. The application of advanced 2D IR spectroscopy to vibrational polaritons challenges and advances our understanding in both fields. First, the 2D IR spectra of polaritons differ drastically from free uncoupled excitations and a new interpretation is needed. Second, 2D IR uniquely resolves excitation of hybrid light–matter polaritons and unexpected dark states in a state-selective manner, revealing otherwise hidden interactions between them. Moreover, 2D IR signals highlight the impact of molecular anharmonicities which are applicable to virtually all molecular systems. A quantum-mechanical model is developed which incorporates both nuclear and electrical anharmonicities and provides the basis for interpreting this class of 2D IR spectra. This work lays the foundation for investigating phenomena of nonlinear photonics and chemistry of molecular vibrational polaritons which cannot be probed with traditional linear spectroscopy.

Application of FT-IR Spectrometry to Determine the Global Metabolic Adaptations to Physical Conditioning in Sportsmen

2002 ◽  
Vol 56 (10) ◽  
pp. 1259-1267 ◽  
Author(s):  
Cyril Petibois ◽  
Georges Cazorla ◽  
André Cassaigne ◽  
Gérard Déléris
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Ir Spectra ◽  
Plasma Concentrations ◽  
Physical Conditioning ◽  
Ir Spectrometry ◽  
Metabolic Adaptations ◽  
Spectral Area ◽  
Ft Ir

Global metabolic adaptations to physical conditioning were described in 15 subjects by FT-IR spectrometry as the method allowed determination of glucose (Glc), lactate (La), glycerol, triglycerides (TG), fatty acyl moieties (FAM), and total amino acids plasma concentrations. Subtraction of plasma FT-IR spectra obtained at resting state from the exercise spectra also allowed determination of the biomolecular response to exercise. On week 1, exercise induced a transient hypoglycemia, a lactatemia increase of 153%, a FAM depletion of 27%, and a TG concentration decrease of 28%. Protein contents increased by 2%, but these were partly catabolized for amino acid supply (+27%), suggesting an important metabolic stress during exercise. On week 3, exercise hypoglycemia had disappeared, lactate increase was diminished by 91%, TG contents were decreased by 14%, and proteins and amino acids exhibited higher absorption increases. On week 5, TG and FAM concentrations were markedly increased during exercise, protein absorption was still increased (+9%), but amino acid blood release was diminished by 81%. These results described positive adaptations to training. Furthermore, FAM concentration could be determined from plasma FT-IR spectra by using the 2996–2819 cm−1 spectral area [ νas(CH3), νas(CH2), νs(CH3), and νs(CH2) absorbance; 0.82 mMol·L−1, a.u. cm−1], as well as for amino acid concentration by using the ν(COO−) spectral area (1430–1360 cm−1; 0.062 g·L−1, a.u. × cm−1). FT-IR spectrometry was useful to determine simultaneously various plasma concentrations and most of the biomolecular changes through successive samples.

Two-Dimensional Correlation Analysis of Temperature-Dependent FT-IR Spectra of Oleic Acid

2013 ◽  
Vol 46 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Miriam Unger ◽  
Deepika Chaturvedi ◽  
Soni Mishra ◽  
Poonam Tandon ◽  
Heinz W. Siesler
Keyword(s):  
Oleic Acid ◽  
Correlation Analysis ◽  
Ir Spectra ◽  
Two Dimensional ◽  
Temperature Dependent ◽  
Ft Ir

Time-Resolved Impulse Photoacoustic Measurements by Step-Scan FT-IR Spectrometry

1996 ◽  
Vol 50 (7) ◽  
pp. 939-947 ◽  
Author(s):  
Boiana O. Budevska ◽  
Christopher J. Manning
Keyword(s):  
Phase Modulation ◽  
Depth Profiling ◽  
Photoacoustic Signal ◽  
Time Dependent ◽  
Solid Samples ◽  
Time Resolved ◽  
Ir Spectrometry ◽  
Photoacoustic Spectra ◽  
Interferometric Phase ◽  
Ft Ir

An impulse/response approach for measuring photoacoustic spectra is described. Instead of the usual modulation from either a chopper or an interferometric phase modulation, a radiation pulse is used to generate the photoacoustic (PA) signal at each step of a step-scan FT-IR spectrometer. The signal from the PA cell is recorded as a time-resolved sequence. The time-dependent photoacoustic signal reveals depth-profiling information for solid samples. Examples of time-resolved impulse photoacoustic spectra (TRIPAS) of gas and solid samples are presented.

Recent Developments in Two-Dimensional Infrared (2D IR) Correlation Spectroscopy

1993 ◽  
Vol 47 (9) ◽  
pp. 1317-1323 ◽  
Author(s):  
I. Noda ◽  
A. E. Dowrey ◽  
C. Marcott
Keyword(s):  
Ir Spectroscopy ◽  
Ir Spectra ◽  
Correlation Method ◽  
External Perturbation ◽  
Correlation Spectroscopy ◽  
Two Dimensional ◽  
2D Ir ◽  
Different Types ◽  
Recent Developments ◽  
Arbitrary Time Dependence

Recent developments in two-dimensional infrared (2D IR) correlation spectroscopy are reviewed. Since the initial introduction of the basic concept seven years ago, the field of 2D IR spectroscopy has evolved considerably. The method for generating 2D IR spectra from perturbation-induced time-dependent fluctuations of IR intensities and the properties of such 2D spectra are summarized first. Applications of 2D IR spectroscopy are then surveyed, and improvements in the instrumentation are reviewed. Different types of external perturbation schemes capable of inducing dynamic fluctuations of IR spectra are listed. Finally, a new 2D correlation method for dynamic spectral data with arbitrary time-dependence is discussed.

One- and Two-Dimensional Infrared Time-Resolved Spectroscopy Using a Step-Scan FT-IR Spectrometer: Application to the Study of Liquid Crystal Reorientation Dynamics

1993 ◽  
Vol 47 (9) ◽  
pp. 1354-1366 ◽  
Author(s):  
Tatsuhiko Nakano ◽  
Toru Yokoyama ◽  
Hirokazu Toriumi
Keyword(s):  
Liquid Crystal ◽  
Data Collection ◽  
Time Dependence ◽  
Rotational Relaxation ◽  
Two Dimensional ◽  
Time Resolved ◽  
Frequency Correlation ◽  
Time Resolved Spectroscopy ◽  
Ft Ir ◽  
Reorientation Dynamics

This paper describes the advances in step-scan FT-IR time-resolved spectroscopy (TRS) and its application to the study of liquid crystal reorientation dynamics. The most important advantage of step-scan interferometry lies in the fact that the optical retardation of the interferometer is held constant during the sampling of interferogram elements, and consequently the spectral multiplexing is decoupled from the time dependence of data collection. This feature of step-scan interferometry allows us to perform both time-domain (one-dimensional time-resolved spectroscopy: 1D TRS) and frequency-domain (two-dimensional frequency correlation spectroscopy: 2D IR) dynamic experiments without the need to deconvolute the time dependence of the sample response from that of the data collection process. The design of the step-scan FT-IR spectrometer used in this study (Bio-Rad FTS60A/896), the experimental setup for 1D and 2D TRS measurements, and the results of a performance test are detailed. The FT-IR TRS techniques applied to the dynamic analysis of liquid crystals have revealed new information that enables us to penetrate into detailed sub-molecular mechanisms of the electrically induced liquid crystal reorientation. The results include the following: (1) 1D FT-IR TRS with microsecond time resolution has been able to follow the real-time transition dynamics of each individual functional group in the molecule; (2) 2D FT-IR TRS, capable of analyzing spatial and temporal correlations between reorientational motions of different sub-molecular segments, has shown that a flexible chain appended to a rigid core of the liquid crystalline molecule undergoes a fast local motion in addition to the rotational relaxation motion of the entire molecule; and (3) 2D frequency correlation analyses have been able to isolate a hidden absorption band and have suggested a possible assignment of this new band. It is emphasized that all these results have been obtained by taking the advantage of time-resolved spectroscopy that provides both temporal and spectral information simultaneously. The results presented in this paper should illustrate the potential applicability of FT-IR TRS to the study of a wide variety of time-dependent phenomena.

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