Raman spectroscopy method for simultaneously measuring temperature and thermal stress of two-dimensional film material in situ

Patent metadata

Field	Value
Publication number	US-11137245-B2
Application number	US-202016877770-A
Country	US
Kind code	B2
Filing date	May 19, 2020
Priority date	Oct 9, 2019
Publication date	Oct 5, 2021
Grant date	Oct 5, 2021

Abstract

Provided is a Raman spectroscopy method for simultaneously measuring a temperature and a thermal stress of a two-dimensional film material in situ. The method includes: providing the two-dimensional film material including a suspended part and a supported part and measuring Raman signals of the suspended part and the supported part; establishing equations of a Raman shift with temperature and a Raman shift with thermal stress for each of the suspended part and the supported part, and solving simultaneous equations to obtain coefficients with temperature and thermal stress; and scanning a characteristic Raman spectrum field of the two-dimensional film material and obtaining a temperature distribution and a thermal stress distribution of the two-dimensional film material according to the characteristic Raman spectrum field in combination of the coefficients of the Raman shift with temperature and the Raman shift with thermal stress.

First claim

What is claimed is:

1. A Raman spectroscopy method for simultaneously measuring a temperature and a thermal stress of a two-dimensional film material in situ, comprising:
(1) providing the two-dimensional film material comprising a suspended part and a supported part having stress states different from each other, and measuring Raman spectroscopy signals of the suspended part and the supported part of the two-dimensional film material;
(2) establishing equations of a Raman shift with temperature and a Raman shift with thermal stress for each of the suspended part and the supported part, and solving simultaneous equations to obtain coefficients of the Raman shift with temperature and the Raman shift with thermal stress for each of the suspended part and the supported part; and
(3) scanning a characteristic Raman spectrum field of a surface of the two-dimensional film material and obtaining a temperature distribution and a thermal stress distribution of the two-dimensional film material according to the characteristic Raman spectrum field in combination of the coefficients of the Raman shift with temperature and the Raman shift with thermal stress.

2. The Raman spectroscopy method according to claim 1 , wherein the two-dimensional film material is a non-metallic material having a Raman characteristic peak.

3. The Raman spectroscopy method according to claim 1 , wherein the two-dimensional film material has a thickness of no more than 1 μm.

4. The Raman spectroscopy method according to claim 1 , wherein the two-dimensional film material is a two-dimensional nano-material.

5. The Raman spectroscopy method according to claim 1 , wherein the step (1) further comprises:
(1-1) placing the two-dimensional film material onto a thermally conductive substrate with a plurality of holes to form the suspended part and the supported part;
(1-2) placing the thermally conductive substrate carried with the two-dimensional film material onto a temperature control platform, and controlling temperatures of the thermally conductive substrate and the two-dimensional film material by changing a temperature of the temperature control platform;
(1-3) maintaining temperatures of the thermally conductive substrate and the two-dimensional film material unchanged via the temperature control platform, focusing a first laser beam on a surface of the suspended part, and measuring a characteristic Raman spectrum of the suspended part and recording a shift of a characteristic Raman spectrum comprising Stoke and anti-Stoke peaks at each of different laser intensities;
(1-4) establishing a temperature rise equation of the two-dimensional film material according to frequencies of the Stoke and anti-Stoke peaks obtained in step (1-3), and calculating a temperature rise of the two-dimensional film material generated at each of the different laser intensities;
(1-5) focusing a second laser beam on a surface of the supported part of the two-dimensional film material and controlling a temperature rise, generated by a laser, of the two-dimensional film material to be not greater than 5 K, increasing the temperature of the thermally conductive substrate via the temperature control platform so as to control the temperature rise of the two-dimensional film material to be consistent with the temperature rise calculated in step (1-4), and measuring and recording a shift of a characteristic Raman spectrum of the two-dimensional film material at each of different temperatures of the thermally conductive substrate.

6. The Raman spectroscopy method according to claim 5 , wherein in the step (1-4), after the two-dimensional film material is heated by the laser, the two-dimensional film material meets the following temperature equation:

I

A
⁢
S

I
S

=

(

ω
1

+

ω
v

)

4

(

ω
1

-

ω
v

)

4

⁢

exp
⁡

(

-

h
⁢

ω
v

k
B

⁢

T
m

)

where I S represents an amplitude of the Stoke peak of the two-dimensional film material and I AS represents an amplitude of the anti-Stoke peak of the two-dimensional film material, ω 1 represents a laser frequency, ω v represents a frequency of a characteristic Raman peak, h represents the Planck constant, k B represents the Boltzmann constant, and T m represents an average temperature of the two-dimensional film material.

7. The Raman spectroscopy method according to claim 5 , wherein the step (2) further comprises:
establishing the following equation of the Raman shift of the suspended part obtained from the step (1-3):
Δω sus =A T ΔT m −A S σ 2D

establishing the following equation of the Raman shift of the supported part obtained from the step (1-5):
Δω sup =A T ΔT m −A S σ 2D +A S ∫ T 0 T m ( E sub α sub −E 2D α 2D ) dT

where Δω sus represents a shift of a characteristic Raman spectrum of the suspended part, and Δω sup represents a shift of a characteristic Raman spectrum of the supported part;
Δ T represents a shift coefficient with temperature, and A s represents a shift coefficient with thermal stress;
σ 2D represents a thermal stress of the two-dimensional film material;
α sub represents a thermal expansion coefficient of the thermally conductive substrate, and α 2D represents a thermal expansion coefficient of the two-dimensional film material;
E sub represents an elastic modulus of the thermally conductive substrate, and E 2D represents an elastic modulus of the two-dimensional film material; and
T 0 represents a temperature of the thermally conductive substrate, T m represents an average temperature of the two-dimensional film material, and ΔT m represents an average temperature rise of the two-dimension

Assignees

• Univ Tsinghua

Inventors

• Zhang Xing
• Wang Haidong
• Liu Hexin

Classifications

• G01K11/00

  Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 · CPC title

• G01D21/02 Primary

  Measuring two or more variables by means not covered by a single other subclass · CPC title

• G01B11/16 Primary

  for measuring the deformation in a solid, e.g. optical strain gauge · CPC title

• G01L1/24

  by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis {using infrared, visible light, ultraviolet} · CPC title

• G01N21/65

  Raman scattering · CPC title