A Multispectrum Fitting Program Based on Non-Linear Least-Squares Method for Line Parameters: Application to 12CH4

Hong-liang MA; Jian-jie ZHENG; Qiang LIU; Xian-mei QIAN; Wen-yue ZHU

doi:10.3964/j.issn.1000-0593(2021)12-3887-05

Journals >Spectroscopy and Spectral Analysis >Volume 41 >Issue 12 >Page 3887 > Article

Spectroscopy and Spectral Analysis
Vol. 41, Issue 12, 3887 (2021)

A Multispectrum Fitting Program Based on Non-Linear Least-Squares Method for Line Parameters: Application to ¹²CH₄

Hong-liang MA^*, Jian-jie ZHENG^{1; 3; 4;}, Qiang LIU^{1; 3; *;}, Xian-mei QIAN^{1; 3;}, and Wen-yue ZHU^{1; 3;}

Author Affiliations

1. Key Laboratory of Atmospheric Optics, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China

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DOI: 10.3964/j.issn.1000-0593(2021)12-3887-05 Cite this Article

Hong-liang MA, Jian-jie ZHENG, Qiang LIU, Xian-mei QIAN, Wen-yue ZHU. A Multispectrum Fitting Program Based on Non-Linear Least-Squares Method for Line Parameters: Application to ¹²CH₄[J]. Spectroscopy and Spectral Analysis, 2021, 41(12): 3887 Copy Citation Text

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Fig. 1. Simplified flow diagram of the multispectrum fitting program

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Example of multispectrum fitting program operation of with four spectra(a): The measured (in scatter line) and calculated (in solid line)line profiles with a multi-peak fitting program; (b): The corresponding fitting residuals

Fig. 2. Example of multispectrum fitting program operation of with four spectra
(a): The measured (in scatter line) and calculated (in solid line)line profiles with a multi-peak fitting program; (b): The corresponding fitting residuals

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输入参数	意义
Ω₂₉₆	296 K下分子的总配分函数
P	实验压强
T	实验温度
Ω_T	实验温度下的配分函数
BASE₀, BASE₁, BASE₂	二次多项式作为光谱基线时, 各次项的初始参数
IFLG	判断是否拟合该基线参数, 0表示固定, 1表示拟合
f	实验噪声水平
THE NUMBER OF TRANSITION	拟合的每张光谱中包含的跃迁谱线条数
ν₀	平移后的谱线中心位置初始值
γ_D	跃迁谱线的多普勒展宽半高半宽初始值
γ_P	跃迁谱线的压力展宽半高半宽初始值
A	跃迁谱线的面积初始值
S_H	数据库中相应谱线的强度
E	跃迁谱线的下能级值

Table 1. The initial parameter names and meanings of the model

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名称	意义
读取实验数据和文件名	将方框1中两列ASCII原始实验数据和方框2中与实验数据对应的TXT文件名称读取到主程序相应的内存中
读取模型参数	将方框3之前存储的拟合参数的初始值和实验条件读取到主程序中
寻找极值	搜索实验数据数组的最小值和最大值, 利用最小二乘拟合确定谱线中心位置
计算频率谱	利用当前参数计算频率谱
拟合光谱	对具有给定初始参数的数据执行最小二乘拟合, 并返回一组最佳拟合参数
输出参数	存储拟合之后的光谱数据及相应的谱线参数

Table 2. The data processing and significance of the main program

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操作步骤名称	意义
HOW MANY SPECTRA DO YOU WANT TO SIMULATE	输入需要拟合几张光谱(即方框1中文件数量)
PLEASE INPUT THE ZERO FREQUENCY	输入谱线的中心频率平移值
ABSORPTION SPECTRUM: 2; TRANSMISSION SPECTRUM: 1	选择拟合光谱数据是发射谱还是吸收谱
SPECTRUM RECORDED AT THE SAME EXPERIMENTAL CONDITION? YES: 1; NO: 0	选择拟合光谱文件是否在同一实验条件下获得
DO YOU WANT TO PROCESS THE GLOBAL FITTING? YES: 1; NO: 0	是否需要进行全局拟合

Table 3. The execution steps and significance of the main program

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$ν_{0}^{b}$ /cm^-1	T/K	空气展宽系数/(cm^-1·atm^-1)
$ν_{0}^{b}$ /cm^-1	T/K	$γ_{ref}^{air}$	$γ_{TW}^{air}$	$(\frac{γ_{ref}^{air} - γ_{TW}^{air}}{γ_{TW}^{air}})$ /%
2 958.017 3	296.0±0.3	0.057 6(4)	0.057 7(3)	-0.17
	251.0±0.2	0.065 1(4)	0.065 3(3)	-0.31
	223.0±0.2	0.071 7(12)	0.071 9(3)	-0.28
	198.0±0.2	0.077 8(1)	0.078 2(4)	-0.51
	173.0±0.3	0.086 9(16)	0.088 4(8)	-1.7
2 958.120 0	296.0±0.3	0.064 9(3)	0.065 5(2)	-0.92
	251.0±0.2	0.075 2(3)	0.075 3(1)	-0.13
	223.0±0.2	0.083 6(3)	0.082 3(3)	1.58
	198.0±0.2	0.092 1(1)	0.092 1(2)	0
	173.0±0.3	0.104 2(6)	0.104 4(3)	-0.19
2 958.2329	296.0±0.3	0.064 1(10)	0.066 3(7)	-3.32
	251.0±0.2	0.074 0(3)	0.075 7(2)	-2.24
	223.0±0.2	0.082 1(7)	0.083 5(4)	-1.68
	198.0±0.2	0.089 7(9)	0.092 5(3)	-3.03
	173.0±0.3	0.100 2(16)	0.103 9(10)	-3.56
2 958.5364	296.0±0.3	0.060 1(7)	0.061 0(4)	-1.48
	251.0±0.2	0.069 3(5)	0.070 9(5)	-2.26
	223.0±0.2	0.076 1(10)	0.077 7(7)	-2.06
	198.0±0.2	0.083 2(2)	0.086 1(3)	-3.37
	173.0±0.3	0.092 2(12)	0.095 9(8)	-3.86
2 958.650 8	296.0±0.3	0.061 5(1)	0.063 6(6)	-3.30
	251.0±0.2	0.070 1(6)	0.071 0(5)	-1.27
	223.0±0.2	0.076 5(9)	0.080 5(8)	-4.97
	198.0±0.2	0.083 4(9)	0.085 2(8)	-2.11
	173.0±0.3	0.092 5(15)	0.097 1(14)	-4.74
2 958.682 5	296.0±0.3	0.055 8(18)	0.056 9(10)	-1.93
	251.0±0.2	0.063 9(4)	0.065 8(3)	-2.89
	223.0±0.2	0.070 0(6)	0.071 3(5)	-1.82
	198.0±0.2	0.077 4(8)	0.081 4(3)	-4.91
	173.0±0.3	0.086 4(21)	0.089 9(18)	-3.89

Table 4. The air-broadening coefficients of ¹²CH₄ derived from the multispectrum fitting program and the difference between them and those from Ref. [7]

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