光谱分析总结

1 Introduction

2 Spectrum theory

3 Spectroscopy instruments

4 UV-Vis spectrum

5 Fluorescence spectrum

6 Infrared and Raman spectrum

7 Near infrared spectrum

8 Image spectrum technique

9 Laser spectroscopy

Spectrum theory

spectrum instruments

Conventional spectroscopy

Laser spectroscopy

1J ≈ 6.24150 ⨯1018eV

h = 6.62607 ⨯10-34 J ⋅s

Absorption spectrum

Emission spectrum（Monochromatic light）

#Fluorescence (emission from excited electronic singlet states)

# Phosphorescence (emission from excited electronic triplet states)

Blue light has a shorter wavelength and is scattered more than red light so the sky appears blue. As the light from the sun travels through more atmosphere more of the colours of light are scattered and the sun appears red.

第二章

Electrons, protons, and neutrons are not little particles but they have particle and wave properties like light.

主量子数n (principal quantum number)

角量子数L (orbital angular momentum quantum number)l＝0、1、2、3… (n-1)

L意义: 决定了同一电子层中不同的亚层（能级）。

(1)决定原子轨道和电子云的形状；(2)在多电子原子中配合n一起决定电子的能量。

磁量子数m (magnetic quantum number)

受l 限制，可取包括0、±1、±2、±3……直至±l，共2l+1个数值。

m意义：决定原子轨道和电子云在空间的伸展方向。

自旋量子数s (spin angular momentum quantum number)

Photoionization（光致电离）

A high‐energy photon can remove an electron from an atom.

If atoms are densely crowded, energy levels are perturbed by neighboring charges

random shifts of energy levels

random shifts of photon energies

broadening of spectral lines

Solids, liquids, and very dense gases emit continuous spectra

分子光谱的特点：带光谱、谱带组，光谱的特点反映了分子的三种运动：

(1)电子运动

与原子中电子的束缚能相近,跃迁时发出可见光、紫外光

(2)分子转动

光谱波长：量级，远红外区

(3)分子振动

光谱波长是量级，近红外区

WA VE PARTICLE DUALITY

light interact with matter：Reflected（反射），Transmitted（透射），Absorbed（吸收），Refracted（折射）various possible types of spectra

Absorption；Reflection；Transmission；Emission

Emission

Absorption

包括一般吸收和选择性吸收

一般吸收，吸收强度与波长无关，比如：白光被物体吸收后透射光仍是白光选择性吸收，吸收强度与波长相关，某些波段吸收特强

跃迁定律：只有引起电偶极距变化的跃迁才是允许的（Allowed and Forbidden Transitions）

Light scattering

光束通过不均匀介质所产生的偏离原来传播方向, 向四周散射的现象

按散射颗粒大小

米氏散射，大，散射强度不随波长显著变化

瑞利散射，小，散射强度与波长4次方成反比

【米氏散射和瑞利散射均为弹性散射，不产生新的波长】

Rayleigh Scattering

Shorter wavelengths scattered much more than longer wavelengths

•Air molecules (N2 and O2) just the right size to very effectively scatter the shorter wavelengths (blue light) of incident solar radiation => blue sky

Size of N2 molecule: 0.31 nm

Size of O2 molecule: 0.29 nm

红光透过散射物的穿透力比蓝光强，所以在拍摄薄雾景色时，可在照相机物镜前加上红色滤光片以获得更清晰的照片。

Mie Scattering

散射光强几乎与波长无关，如观察白云对阳光的散射，各波长的光都大致均等地被散射，所以晴空的云是白色的。

当大气中粒子的直径与辐射的波长相当时发生的散射称为米氏散射