显微共焦拉曼光谱

年代有什么关系，但发现1080cm-1的拉曼峰
的强度与位于高波数的荧光峰强度的比值与
年代有关。
给出一个经验公式：
y=a+bx x= 年代
y=log(I1080/I荧光) a=-25.384 b=0.013
Why SERS spectroscopy?
Raman spectroscopy:
▪ high characteristic ▪ good spatial resolution (micro Raman) ▪ minimal sample preparation ▪ all solvents can be used but: ▪ biological samples often show high fluorescence ▪ biological molecules appear often at low concentration level
Focal volume (cylindrical)
Baldwin, Batchelder, Webster: “Raman Microscopy: Confocal and Scanning Near-Field“, in: Handbook of Raman Spectroscopy
Confocal Raman Microspectroscopy
水拉曼特征峰随NaCl 浓度变化趋势图,曲线A, B,C,D , E,F的盐度分别为:0.05 ,0.20 ,0.50 ,1.00 ,2.00
,5.00mol/ L
W/Si多层膜
年代估计
Bertoluzza等对28个年代在1750~1940年之
间的工艺玻璃杯 进行了拉曼光谱分析，仅从
拉曼峰的位置和强度并不能反映出与样品的
Typical SERS media
Resonance with electronic states
Virtual state
r
w0 =
wir
wir
w0
wStokes
f i
wR
f i
Continuum Resonance Raman Scattering in Iodine Excited with l0 = 488 nm
l0 = 488 nm
Wavenumber/cm-1
TS-1 的紫外共振拉曼光谱
lex=244 nm
Integration 来自百度文库f the Microscope and the Spectrometer: Microscope
Microscope + Spectrometer
dispersing element: grating monochromator Baldwin, Batchelder, Webster: “Raman Microscopy: Confocal and Scanning Near-Field“, in: Handbook of Raman Spectroscopy
从拉曼光谱获取的信息
characteristic Raman peak
changes in frequency of Raman peak
width of Raman peak
polarization of Raman peak
Composition and structure of material
Raman Intensity Raman Intensity
NH2
N
N
N H
N
Raman
10-1 M 10-2 M 10-3 M
SERS
10-5 M 10-6 M 10-7 M
1500
1000
500
Wavenumber / cm-1
10-8 M
1500
1000
500
Wavenumber / cm-1
Principle of Confocal Microscopy and Depth Discrimination:
显微共焦拉曼光谱及应用
左健
中国科学技术大学 理化科学实验中心
拉曼光谱是以光子为探针，它对 样品的结构和成分极为敏感并有很强 的特征性,就像人的指纹一样。
特别是显微拉曼光谱可进行空间分 辨、原位无损的光谱分析。
Raman Spectrum of CCl4
435.8 nm (Hg-line) anti-Stokes Stokes
Confocal Raman Microspectroscopy
Making the Microscope Confocal: Introducing an Aperture
Focal length of the lense Effective diameter at the lense
Beam waist of diameter (Gaussian intensity profile)
stress/strain state Crystal size
quality of crystal(crystal size)
crystal (molecule) symmetry and orientation
不同的物质，其拉曼谱是不同的，就象人的指纹 一样，因此拉曼光谱可用于物相的分析与表征。
Exposure time: ca. 40 hours
Spectrum taken with a modern Raman set-up; Resolution ca. 0.5 cm-1 Sample Volume: ca. 1 ml Accumulation time: ca. 1 s
453.4-CCl235Cl237
SERS quenches fluorescence
Raman silver colloids
M. x piperita 514.5 nm
Raman Intensity
10 mm
essential oil
2000
1500
1000
500
Wavenumber / cm-1
SERS improves the detection limit: Adenine
Spectrum taken by Raman in 1929; Resolution ca. 10 cm-1
Sample Volume: ca. 1 liter
Isotopic (35,37Cl) splitting of n1vibration
461.5-CCl435
455.1-CCl335Cl37