spectroscopy and its application chemical and biological detection professor: nam sun wang haimo liu...
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![Page 1: Spectroscopy and its Application Chemical and Biological detection Professor: Nam Sun Wang Haimo Liu 12/04/2007](https://reader035.vdocuments.mx/reader035/viewer/2022062409/56649d625503460f94a452fb/html5/thumbnails/1.jpg)
Spectroscopy and its Application
Chemical and Biological detectionProfessor: Nam Sun Wang
Haimo Liu12/04/2007
![Page 2: Spectroscopy and its Application Chemical and Biological detection Professor: Nam Sun Wang Haimo Liu 12/04/2007](https://reader035.vdocuments.mx/reader035/viewer/2022062409/56649d625503460f94a452fb/html5/thumbnails/2.jpg)
Spectrum and Spectroscopy
Spectrum: (a). Different colors observed when
the white light was dispersed through the prism
(b). The changing of light intensity as a function of frequency
Spectroscopy: Study of spectrum, to identify substances
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Spectroscopy
Types of spectroscopy:(a) Continuous spectroscopy(b) Absorption spectroscopy(c) Emission spectroscopy
![Page 4: Spectroscopy and its Application Chemical and Biological detection Professor: Nam Sun Wang Haimo Liu 12/04/2007](https://reader035.vdocuments.mx/reader035/viewer/2022062409/56649d625503460f94a452fb/html5/thumbnails/4.jpg)
Emission ProcessElectrons ground level
High energy level
Absorb energy
En
erg
y e
missio
n
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EquipmentLeft: Equipment diagram
Right: Schematic diagram
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Applications
Absorption spectrum: used in deducing the presence of elements in stars and other gaseous objects which cannot be measured directly.
Emission spectrum: provide a definition of the spectrum of each atom, used to be compared with absorption spectrum
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Spectrum of planets
Compare the absorption spectrum with the element’s emission spectrum, people can build the spectrum of planets.
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Fluorescence Spectroscopy
Light source, self-emission which means the electrons transferred to the lowest level spontaneously
Different fluorescence: (a) different meta-stable
states (b) different various
vibrational states of the ground state
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Time-resolved fluorescence spectroscopy
It provides fluorescence intensity decay in terms of lifetimes
Advantages:enhance the discrimination among
fluorophores (overlapping emission spectra )
sensitive to various parameters of the biological microenvironment
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Time-resolved fluorescence spectroscopy
Time-resolved laser-induced fluorescence spectroscopy (tr-LIFS)
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Mathematical method[ ] [ [ ]]y n T x n
[ [ ] [ ]] [ [ ]] [ [ ]]T x n y n T x n T y n
[ [ ]] [ [ ]]T x n T x n
[ ] [ ] [ ]k
x n x k n k [ [ ]] [ [ ] [ ]
k
T x n T x k n k
![Page 12: Spectroscopy and its Application Chemical and Biological detection Professor: Nam Sun Wang Haimo Liu 12/04/2007](https://reader035.vdocuments.mx/reader035/viewer/2022062409/56649d625503460f94a452fb/html5/thumbnails/12.jpg)
Mathematical method
[ [ ]] [ ] [ [ ]]k
T x n x k T n k
[ ] [ ] [ [ ]]k
y n x k T n k
[ ]x[ ] [ [ ]]h x T x
If is an impulse, then the impulse response will be
[ ] [ [ ]]h n k T n k
[ ] [ ] [ ]k
y n x k h n k
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Mathematical method
Based on the definition of convolution:
( )( ) ( ) ( )n
f g m f n g m n
[ ] ( )[ ] [ ] [ ]y n x h n x n h n
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Mathematical method
For the tr-LIFS system, the impulse response function is what would be recorded as the observed fluorescence decay
( )IRF t
( )F t
( ) ( ) ( )F t I t IRF t
Estimation of the intrinsic fluorescence decay was carried out via deconvolution of the observed fluorescence
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Spectral Imaging system Imaging provides
intensity at every pixel of the image I (x, y)
spectrometer provides the intensity of a single spectrum, I(λ)
spectral image provides a spectrum at each pixel, I (x, y, λ)
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Observation of multiple activities
Trying to use 5 different kinds of fluorescent molecules to label each of the 24 chromosomes in human body
2 to 5 minus 1=31
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Observation of multiple colors
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Living cell spectral imaging
Compromise: only two kinds of cellular organ were labeled
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¿Questions?