Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Raman Effect And Micro-raman Spectroscopy拉曼效應與微拉曼光譜儀

Student : 王維勤Student ID : MA2L0205

Advisor : 吳坤憲

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Outline• Introduction• Raman effect• Micro-Raman Spectroscopy

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Why the Oceans Are Blue?

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Introduction• In 1928, C.V.Raman found when the light is scattered, the

frequency of scattering light will change in the gas and liquid. The change in frequency is determined the material characteristics when it scattering light.

C. V. Raman (1888-1970)

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Introduction

Incident Light 0

Reflected light 0

Transmitted light 0

elastic scattering Light 0

0

inelastic scattering light

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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• Scattering light most belong to the elastic scattering, also known as Rayleigh scattering.

• Very small portion of the scattered light are inelastic scattering, the frequency will change after scattering.

• E=h0

• Generate energy exchange, and energy of the incident light are not the same.

Introduction

0

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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• Inelastic scattering also known as Raman scattering, refers to the frequency changing when the light are scattered.

• When light enters the sample surface and molecular collisions, the molecular excitation energy to a virtual state, then scattering way to release energy.

Raman Effect

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Raman Effect

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Raman Effect• Scattering Light

① Scattering Light Frequency = Incident Light Frequency (Rayleigh Scattering)

② Scattering Light Frequency > Incident Light Frequency (Anti stokes line)

③ Scattering Light Frequency = Incident Light Frequency (Stokes line)

Stoke lineE=h(0 - )

Anti Stokes lineE=h(0 + )

一般偵測拉曼光譜偵測的是散射光子與入射光子的頻率差，稱之為 Raman shift。

0 - 0 + 0

Stoke line Rayleigh Scattering Anti Stokes line

= 0 - (0 - )

= (0 + ) - 0

=

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Micro-Raman Spectroscopy

Laser sample

Spectroscope

CCDcomputer

利用 CCD(光學多頻道分析儀 )的拉曼光譜儀

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Micro-Raman Spectroscopy

Sample

Incident Light

Scattering light

Reflected light

Sample

Sample

Sample

Incident Light

Scattering light

Scattering lightScattering light

Incident Light Incident Light

Incident Light

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Micro-Raman Spectroscopy

探測器

分光儀 (光譜儀 )

前置單色器

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Micro-Raman Spectroscopy

Laser wavelength : 325nm、 532nm、 633nm

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Micro-Raman measurements

Micro -Raman measurements are performed at room temperature under excitation at 532 nm of Nd: YAG laser.

根據橫向光學聲子模型可以得知(Transverse Optical phonon, TO mode)非晶鍺 -鍺鍵結光譜峰值位於 ~270cm-1

結晶鍺 -鍺鍵結光譜峰值位於 ~300cm-1

鍺 -矽鍵結光譜峰值位於 ~400cm-1

非晶矽 -矽鍵結光譜峰值位於 ~486cm-1

結晶矽 -矽鍵結 ~520cm-1

Film thickness ~ 100nm

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Micro-Raman measurements• According to the transverse optical phonon model

(TO mode), we can know: • The peak position indicates the composition and structure

of the sample.• Intensity spectrum shows the concentration of an

ingredient

Advanced Nano-technology and Applied Optoelectronics Lab.Southern Taiwan University of Science Technology

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Thanks for your attention