光谱学与光谱分析
光譜學與光譜分析
광보학여광보분석
SPECTROSCOPY AND SPECTRAL ANALYSIS
2010年
2期
297-300
,共4页
激光光谱学%光声光谱%二能级%NO%缓冲气体
激光光譜學%光聲光譜%二能級%NO%緩遲氣體
격광광보학%광성광보%이능급%NO%완충기체
Laser spectroscopy%PA spectrum%Two energy-level%NO%Buffer gas
采用拉普拉斯变换严格求解二能级系统光与物质相瓦作用的速率方程,获得了强激光诱导气体分子系统光声信号的解析表达式.结果显示光声信号的大小与样品分子的吸收截面、激发光强度、分子共振跃迁吸收的光子数、分子碰撞弛豫速率等因素有关.借助于光声信号随激光强度的变化关系,将NO分子在420.0～470.0 nm波长区间的激光诱导光声光谱归属于NO分子经X~2Π→A~2∑的双光子激发跃迁及X ~2Π→E~2∑,F~2∑,R~2∑的三光子激发跃迁,由此获得NO分子A~2∑,E~2∑,F~2∑和R~2∑激发电子态的振动常数分别为2 346,2 342,2 397和2 381 cm~(-1),结果与采用其他方法测量的结果符合得较好.并对光声信号随缓冲气压升高而出现饱和的现象进行了理论解释.
採用拉普拉斯變換嚴格求解二能級繫統光與物質相瓦作用的速率方程,穫得瞭彊激光誘導氣體分子繫統光聲信號的解析錶達式.結果顯示光聲信號的大小與樣品分子的吸收截麵、激髮光彊度、分子共振躍遷吸收的光子數、分子踫撞弛豫速率等因素有關.藉助于光聲信號隨激光彊度的變化關繫,將NO分子在420.0～470.0 nm波長區間的激光誘導光聲光譜歸屬于NO分子經X~2Π→A~2∑的雙光子激髮躍遷及X ~2Π→E~2∑,F~2∑,R~2∑的三光子激髮躍遷,由此穫得NO分子A~2∑,E~2∑,F~2∑和R~2∑激髮電子態的振動常數分彆為2 346,2 342,2 397和2 381 cm~(-1),結果與採用其他方法測量的結果符閤得較好.併對光聲信號隨緩遲氣壓升高而齣現飽和的現象進行瞭理論解釋.
채용랍보랍사변환엄격구해이능급계통광여물질상와작용적속솔방정,획득료강격광유도기체분자계통광성신호적해석표체식.결과현시광성신호적대소여양품분자적흡수절면、격발광강도、분자공진약천흡수적광자수、분자팽당이예속솔등인소유관.차조우광성신호수격광강도적변화관계,장NO분자재420.0～470.0 nm파장구간적격광유도광성광보귀속우NO분자경X~2Π→A~2∑적쌍광자격발약천급X ~2Π→E~2∑,F~2∑,R~2∑적삼광자격발약천,유차획득NO분자A~2∑,E~2∑,F~2∑화R~2∑격발전자태적진동상수분별위2 346,2 342,2 397화2 381 cm~(-1),결과여채용기타방법측량적결과부합득교호.병대광성신호수완충기압승고이출현포화적현상진행료이론해석.
The technique of photoacoustic(PA)spectrum is based on the conversion of photon to acoustic energy by collision quenching of the excited molecules.It holds the characteristic of higher detection sensitivity,wide detection spectral region,no damage to the sample etc.It is used in many scientific observation areas such as gas composition analysis,research on chemistry and biology,environmental monitor and so on.In the present paper,the analytic formula of the PA signal produced from the interaction of intense laser with gas system was deduced by solving the dynamic rate equation about the interaction of photon and material.The results show that the magnitude of the PA signal depends on the factors of molecular absorption cross-section,laser intensity,photon number absorbed by the molecule and collision relaxation rate.With the aid of the relation of the PA signal versus laser intensity,the PA spectrum of NO molecule in the wavelength region of 420.0-470.0 nm is ascribed to the transition of X~2Π(v"=0)→A~2∑(v'=0,1)and X~2Π(v"=0)→E~2∑(v'=2,3,4),F~2∑(v'=1,2,3)and R~2∑(v'=0,1).These transitions are realized via two or three-photon process.The vibration constants of NO A~2∑,E~2∑,F~2∑ and R~2∑.electronic states were calculated from the wavelength of the spectral peaks.They are 2 346,2 342,2 397 and 2 381 cm~(-1) respectively.The results are consistent with the one of other method.The phenomenon of saturation appears when the buffer gas pressure is high enough.This is owing to the finite excited molecules.
