塞曼调制磁旋转光谱技术在磁场测量中的应用

首次提出采用塞曼调制－磁旋转光谱技术制成ＮＯ２分子磁场计的可能性．并对不同进场下，ＮＯ２分子塞曼调制磁旋转光谱１６８４６．２０ｃｍ－１谱线强度进行了测量，提出了这种新型磁强计的设计原理，并阐述了该磁强计的特点．     

斯塔克调制—电旋转激光光谱技术及其应用

采用斯塔克调制电旋转激光光谱技术将由偶然简并能级跃迁产生的电旋转信号从非简并能级跃迁中分离出来，因而简化了转动量子态的跃迁谱线，减少了谱线重叠现象，反映了分子能级受偶然简并斯塔克相互作用以及电四极相互作用的特性，非常适合那些转动谱线密集，微扰严重的多原子分子的光谱测量与分析。本文既给出了这种光谱技术的半经典理论模型，又运用微扰理论解释了用该技术所测的ＮＯ２分子的转动光谱的形成原因和它们的主要特征。     

塞曼调制磁旋转光谱技术在磁场测量中的应用

首次提出采用塞曼调制-磁旋转光谱技术制成NO₂分子磁场计的可能性.并对不同进场下,NO₂分子塞曼调制磁旋转光谱16846.20cm^-1谱线强度进行了测量,提出了这种新型磁强计的设计原理,并阐述了该磁强计的特点.     

光外差-磁旋转-浓度调制光谱技术

介绍了一种针对瞬态分子光谱测量的新技术:光外差磁旋转浓度调制光谱技术,这种光谱技术具有很高的灵敏度,综合了光外差探测技术、磁旋转光谱技术和浓度调制光谱技术的特点,利用浓度调制光谱技术针对寿命很短的瞬态分子和激发态分子的光谱进行测量,利用光外差探测技术可以消除来自光源的幅度涨落噪声,实现散粒噪声的测量极限,利用磁旋转光谱技术可以对顺磁性分子进行选择性的测量,并且进一步提高探测灵敏度。详细讨论了这种光谱技术的工作原理,并用这种技术对O2分子的b1Σg+-X3Σg-三重禁戒跃迁光谱进行测量,获得了很好的测量信噪比。并对该技术的灵敏度作了详细的分析,估计最小相对吸收度可达1.9×10-9以及O2分子三重禁戒跃迁的吸收截面为σ=2.4×10-24cm2。     

磁旋转腔增强光谱技术

为了提高吸收光谱的探测灵敏度,在弱吸收或短光程吸收的情况下实现高灵敏探测,将腔增强光谱技术与磁旋转光谱技术有效地结合起来,发展了高灵敏的磁旋转腔增强吸收光谱技术,并通过测量O2 的三重禁戒跃迁谱线验证了该技术的探测灵敏度。实验采用环型增强腔,以避免光束的返回对激光器的干扰。给出了腔的耦合匹配条件,以及镜面反射率、腔损耗对增强因子的影响;同时也给出了在实验中对光谱信号的处理方法。测量结果表明,在谐振腔精细度为F=48,腔内总损耗为13%,以及腔镜的耦合效率为 95%的情况下,对 O2 分子最小相对吸收度约为4.5×10-8(1 s积分时间)。     

23Na39K分子D1П→X1∑^＋激光感生荧光光谱及强度研究

实验获得了Ａｒ＾＋激光５１４．５ｎｍ线诱导２３Ｎａ３９Ｋ分子产生的Ｄ１П→Ｘ１∑＾＋跃迁荧光谱，通过测量激光感生荧光光谱强度随泵浦功率，热管炉温度及缓冲气压变化规律，详细研究了其跃迁机制，用最小二乘法拟合获得２３Ｎａ３９Ｋ分子Ｘ１∑＾＋态振动动常数，理论计算了种跃迁谱支波长值及Ｆｒａｎｃｋ－Ｃｏｎｄｏｎ因子和光谱强度值，与实验观测值符合得相当好，充分表明本文对激光感生荧光光谱的归属以及对各支谱线振     

一种新型的分子离子吸收光谱技术

将频率调制和磁旋转 技术应用于速度调制激光光谱技术中,形成一种全新的具有高灵敏度的分子离子光谱测量技术,它不仅保留了速度调制光谱技术掏中性分子吸收信号的特点,同时使噪声达到散粒噪声的测量极限。     

激光光谱学

O433.54 2004004057 光外差磁旋转速度调制光谱技术的参量优化=Optimization of optical heterodyne magnetic rotation enhanced velocity modulation spectroscopy[刊,中]/甘雨洁(华东师范大学物理系,光谱学与波谱学教育部重点实验室.上海(200062)),李伟…∥量子电子学报.—2004,21(3).—295-301 光外差磁旋转速度调制光谱技术是一种对离子分子选择性测量的高灵敏激光吸收光谱技术。本文将以N_2~ 和CO~ 为例,主要讨论该技术的高灵敏度和高信噪比的特点,分析影响实验结果的各个参量,介绍光谱信号测量中的优化过程。图9参16(杨妹清)     

钠分子高位态(2~1Π_g)有关振转能级动力学参数的测定

用共振多光子电离光谱技术，检测钠分子Ｘ１Σ＋ｇ→２１Πｇ在１６５７４．５ｃｍ－１～１６５９０．５ｃｍ－１之间的共振电离信号激发谱，根据有关分子常数和德哈姆展开式，标识了其中三条谱线。借助于电离流时间衰减曲线，测量得出了上述三条谱线对应的振动能级的动力学参数     

~（23）Na~（39）K分子D~1∏→X~1∑~＋激光感生荧光光谱及强度研究

实验获得了Ａｒ＋激光５１４．５ｎｍ线诱导２３Ｎａ３９Ｋ分子产生的Ｄ１∏→Ｘ１∑＋跃迁荧光谱．通过测量激光感生荧光光谱强度随泵浦功率、热管炉温度及缓冲气压变化规律，详细研究了其跃迁机制．用最小二乘法拟合获得２３Ｎａ３９Ｋ分于Ｘ１∑＋态振动常数．理论计算了各跃迁谱支波长值及Ｆｒａｎｃｋ－Ｃｏｎｄｏｎ因子和光谱强度值，与实验观测值符合得相当好，充分表明本文对激光感生荧光光谱的归属以及对各支谱线振、转量子数的赋值是合理的．     

塞曼调制磁旋转光谱线型的研究

在研究塞曼调制磁旋转光谱线型的过程中，发现了入射光场的偏振特性地谱线型的影响，从而解释了实验中出现的各种线型，其中包括一些难以解释的除二次微分线型外的其它线型，并且在实验中，得到了理论分析一致的结果，为塞曼调制旋转光谱，激光光谱技术，光谱测量精度的进一步改善提供了参考依据。     

Coherent population trapping magnetometer by differential detecting magneto–optic rotation effect

A pocket coherent population trapping(CPT) atomic magnetometer scheme that uses a vertical cavity surface emitting laser as a light source is proposed and experimentally investigated.Using the differential detecting magneto–optic rotation effect,a CPT spectrum with the background canceled and a high signal-to-noise ratio is obtained.The experimental results reveal that the sensitivity of the proposed scheme can be improved by half an order,and the ability to detect weak magnetic fields is extended one-fold.Therefore,the proposed scheme is suited to realize a pocket-size CPT magnetometer.     

Area-selective signal parameter estimation for two-dimensional MR spectroscopy data

We consider the problem of parametric spectral analysis of two-dimensional (2D) magnetic resonance spectroscopy (MRS) data. Estimating the signal components from 2D MRS data is becoming common practice in many clinical MR applications. The most frequently used signal processing tool for this estimation problem is the non-parametric 2D-FFT. There are several alternative parametric methods available to perform this analysis, yet their computational complexity is generally rather high and it becomes prohibitive when the number of points in the measured data matrix is large. In this paper, we propose a novel signal parameter estimation technique which operates on a pre-specified sub-area of the 2D spectrum. This area-selective approach can be used either to estimate only the signal components of main interest in the data, or to compute signal parameter estimates of all present signal components as the computational burden for each sub-area is low. In the numerical example section we consider both simulated data and in vitro 1H data acquired from a 1.5 T MR scanner.     

基于独立成分分析的全波核磁共振信号噪声滤除方法研究

核磁共振测深(MRS)探水仪探测到的纳伏级微弱信号极易受到各种环境噪声的干扰, 严重影响信号特征参数的准确提取, 导致后续反演解释错误率增高. 针对这一难题, 提出了基于独立成分分析的快速固定点算法进行信噪分离. 首先分析了该算法用于全波MRS信号消噪的适用性; 其次, 采用数字正交法解决欠定盲源分离问题, 提出了频谱校正法实现分离信号幅值的有效恢复. 仿真结果表明, 该算法能够有效地实现全波MRS信号的信噪分离, 且数据拟合后初始振幅和弛豫时间的相对误差小于± 5.00%; 通过与其他经典算法的对比分析, 进一步证明了该算法消噪性能的优越性. 将该算法应用到野外实测信号处理, 结果证明其能有效滤除环境噪声.     

Point-wise measurements of MRS volume selection performance are insensitive to magnetic susceptibility effects of phantom materials

The purpose was to analyse magnetic susceptibility effects on accuracy of point-wise measurements of signal profiles in the assessment of MRS volume selection performance. An existing phantom design consisting of a sphere with a movable signal source was used for the investigation. The influence from the phantom on magnetic field homogeneity was measured with phase sensitive 1H imaging and 31P spectroscopy on a 1.5 T whole body MR system. The susceptibility effects for such a phantom design can be separated in 1/ A variation in the background magnetic field, which is caused by the stationary structures and has a significant influence on spatial accuracy. 2/ A magnetic field distortion, which is caused by the movable signal source and has very little influence on accuracy. The spatial inaccuracy due to susceptibility effects in this phantom, was 0.03 mm for positions of the signal source covering a 40-mm VOI. Susceptibility effects from the movable signal source were substantial but had very little influence on spatial accuracy. Still, improvements of this phantom design are possible. Point-wise measurements using a phantom with a movable signal source is inherently insensitive to susceptibility effects from the signal source and permits accurate signal profile measurements of high spatial (sub-mm) resolution.     

Detection of triplet-singlet transitions by magnetic circular dichroism,with application to the spectrum of acrolein

An apparatus constructed for the purpose of investigating high resolution gas phase magnetic circular dichroism (MCD) spectra of triplet-singlet transitions is described. It has been used to obtain MCD spectra of acrolein with path lengths up to 28 meters and magnetic fields up to 3 kG. Some of the relative merits of MCD and magnetic rotation spectra (MRS) are discussed.     

激光相干场成像散斑噪声复合去噪方法

噪声是影响激光相干场高分辨成像系统像质的重要因素,激光相干场成像系统既受背景光加性噪声影响,又受激光乘性散斑噪声影响.为解决激光相干场成像系统受激光乘性散斑噪声和背景光加性噪声叠加引起的成像像质退化效应问题,从噪声抑制角度提高激光相干场系统高分辨成像像质,研究建立了激光散斑乘性噪声和背景光加性噪声对大气下行链路激光回波场信号影响干扰模型,并基于该模型提出了一种基于同态滤波和稀疏基追踪级联复合去噪算法.首先基于同态滤波理论将激光乘性散斑噪声转化为加性噪声,再由高通滤波器滤除散斑噪声,最后采用基追踪稀疏理论方法抑制背景光等加性噪声对像质的影响.研究表明,较现有单一去噪方法,该级联复合去噪方法可一次性消除激光乘性散斑噪声和背景加性噪声两种不同性质的噪声,有效改善了激光相干场成像质量.