Selective excitation and suppression of coherent anti-Stokes Raman scattering by shaping femtosecond pulses

Femtosecond coherent anti-Stokes Raman scattering (CARS) suffers from poor selectivity between neighbouring Raman levels due to the large bandwidth of the femtosecond pulses. This paper provides a new method to realize the selective excitation and suppression of femtosecond CARS by manipulating both the probe and pump (or Stokes) spectra. These theoretical results indicate that the CARS signals between neighbouring Raman levels are differentiated from their indistinguishable femtosecond CARS spectra by tailoring the probe spectrum, and then their selective excitation and suppression can be realized by supplementally manipulating the pump (or Stokes) spectrum with the $\pi $ spectral phase step.     

胃炎和胃溃疡组织细胞的显微拉曼光谱研究

利用共焦显微拉曼光谱研究了胃炎组织和胃溃疡组织的粘膜细胞。结果表明,与胃炎组织细胞比较,溃疡组织细胞中胞嘧啶的振动峰781 cm-1相对较弱,而腺嘌呤和胸腺嘧啶793,823cm-1处的峰强有所增加; 对应于α螺旋结构蛋白质酰胺Ⅰ和酰胺Ⅲ带的1654和1230～1270cm-1的强度均相对减小,色氨酸特征峰1332cm-1和苯丙氨酸特征峰1003cm-1强度有所降低,同时与色氨酸残基微环境变化密切相关的1554频移到1556cm-1,且强度有所增加;脂类的特征谱线1073 cm-1向高波数频移到了1078cm-1, 对应于CH₂扭转振动的1303cm-1与来自于CH面内变形振动的1268cm-1强度比值减小。上述变化表明两种疾病组织细胞中的核酸,蛋白质和脂类在成分、结构和构型上都存在明显差异;研究发现利用C—H弯曲振动的谱线1449cm-1和蛋白质酰胺Ⅲ带的谱线1660cm-1的强度比值A₁₄₄₉/A₁₆₆₀区分两种疾病具有较好的准确性。     

矩阵方程ATXB+BTXTA=D的极小范数最小二乘解的迭代解法

1 引言 设Rm×n表赤m×n实矩阵的全体,AT表示矩阵A的转置,R(A)和N(A)分别表示矩阵A的值域和零空间.     

Raman spectroscopic identification of normal and malignant hepatocytes

Raman spectroscopy has strong potential for providing non-invasion diagnosis of cancers. In this paper, micro-Raman spectroscopy is used to diagnose one most common liver cancer, hepatocellular carcinoma （HCC）. The statistical analyzes, including t-test, principal component analysis （PCA）, and linear discriminant analysis （LDA）, are performed on the Raman spectra of malignant and normal hepatocytes. The t-test-LDA results show that the 786- and 1004-cm^-1 bands of the malignant and normal hepatocytes are significantly different, and PCA-LDA results show an overall accuracy of 100% for the Raman spectroscopic identification of normal and malignant hepatocytes in our experiment.     

Raman spectroscopic identification of normal and malignant human stomach cells

Micro-Raman spectroscopy is employed to identify the normal and malignant human stomach cells. For the cancer cell, the reduced intensity of the Raman peak at 1250 cm-1 indicates that the protein secondary structure transforms from β-sheet or disordered structures to α-helical, while the increased intensity of the symmetric PO2 stretching vibration mode at 1094 cm-1 shows the increased DNA content. The ratio of the intensity at 1315 cm-1 to that at 1340-1 reduces from 1.8 for the normal cell to 1.1 for the cancer cell in the course of canceration, and the ratio of the intensity at 1655 cm-1 to that at 1450cm-1 increases from 1.00 for the cancer cell to 1.26 for the normal cell which indicates that the canceration of stomach cell may induce saturation of the lipid chain.     

中间能级失谐量对Y型四能级自发辐射量子干涉的影响

文章运用密度矩阵方程，在Y型四能级系统中计算和讨论了中间共振增强能级的失谐对自发辐射量子干涉效应的影响。结果表明，两步激发而非双光子激发是产生自发辐射干涉效应的主要激发机制；失谐量过大，则因两步激发的失效而导致有关量子干涉效应的消失。以上分析对正确选取产生量子干涉效应的能级系统及理解有关过程是很有意义的。     

Study on the interaction of anticancer drug mitoxantrone with DNA by fluorescence and Raman spectroscopies

Mitoxantrone, a clinically useful antitumour antibiotic for leukaemia and breast cancer, has received more attentions. In this paper, the interaction between mitoxantrone and calf thymus DNA is investigated by Raman and fluorescence spectroscopies, and the binding site of mitoxantrone to calf thymus DNA is explored. The results showed that mitoxantrone interacts with calf thymus DNA bases by the intercalation of anthracycline into the base pair plane of adenine (A) and thymine (T), and it results in the disruption of the hydrogen bonds between calf thymus DNA bases, and thus the calf thymus DNA double-strand can be disrupted into the B-form DNA double-strand segments.     

Na原子能量自囚禁的加速效应

采用高分辨激光光谱方法，在较高温度条件下，实验观察到Na原子能量自囚禁加剧特征。出现原子加速的光谱行为；并导致零速度原子碰撞转移到高激发态的速度减少。从原子内能碰撞转移的角度，分析了原子速度分布变异的机理。     

基于碰撞感应激发而产生相干相长的研究

运用半经典密度矩阵方法研究了一个开放四能级系统中基于碰撞感应激发而产生的干涉相长.在该四能级系统中,一个公共上能级与两个间距较大的下能级所组成Λ型三能级量子拍结构由一个相干激光场耦合,同时该公共上能级通过真空模与另一下能级耦合.     

基于碰撞产生的频域和时域内的量子干涉效应研究

从理论和实验两方面对以往较少涉及的原子-分子混合体系中基于碰撞而产生间距较大多能级间的相干和两延时波包间的相干及量子干涉效应进行研究,揭示通过碰撞这种非相干过程可产生在频域内具有较大能级间距多能级间的相干和时域内两延时波包间的相干.运用半经典密度矩阵理论及缀释态理论对碰撞产生的多能级系统量子干涉效应进行计算和分析;同时实验上用ns脉冲染料激光器观察到钠原子-分子混合体系中基于等频双光子两步激发及钠原子-分子混合激发而产生的钠原子3S-3P(1/2,3/2)-5S(或4D)系统基于碰撞产生的频域和时域内的量子干涉效应.本工作为进一步运用非相干碰撞过程研究较大间距多能级间和两延时波包间的相干提供了一种新的有效的方法,可望在高灵敏高精度激光光谱、原子分子激发态结构信息及物理化学过程的控制等方面具有广泛的应用.