Two-Dimensional Infrared Correlation in Time-resolved Spectroscopy

1
Two-Dimensional Infrared Correlation in
Time-resolved Spectroscopy

• Sadeq M. Al - Alawi
• Department of Chemistry
• University of Bahrain
• October 24, 2002

2
Two-dimensional IR spectroscopy

• It is an analytical method based on time-resolved
  detection of IR signals to study molecular
  interaction

3
How does it work?

• When a perturbation is applied to the system,
  various chemical constituents of the system are
  excited.
• The excitation and subsequent relaxation toward
  the equilibrium can be probed with IR.

4

• The forward Fourier transform Y1(?) of the
  dynamic spectral intensity y(?1,t)observed at a
  wavenumber, ?1 is given by

5
Likewise, the conjugate of the Fourier
transform ?2(?) of dynamic spectral intensity
y(?2,t) observed at spectral variable ?2 is given
by

• ?2(?) y(?2,t) eit dt
• ?2re(?) -i ?2im(?)

6
The complex two-dimensional correlation intensity
is defined as

• ?(?1, ?2) i ?(?1, ?2) ?1(?) .
  ?2(?) d?

7

• Noda (1995) proved that the synchronous 2D
  correlation spectrum can be computed without
  Fourier transforming dynamic spectral data
• ?(?1, ?2) y(?1,t) . y(?2,t) dt

8
Advantages

• Simplify complex spectra consisting of many
  overlapped peaks.
• Enhances spectral resolution by spreading peaks
  over the second dimension.
• Enables us to show the infrared bands that change
  together in time.

9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
Singular Value Decomposition SVD

• SVD method provides the mean to determine the
  number of components involved in the
  time-resolved spectra.
• A U . W . Vt
• U defines the eigenvectors of the rows of A
• W represents the variance in the actual data
• V represents the spectral components

16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
Thank U