Femtosecond time-resolved fluorescence non-collinear optical parametric amplification spec- troscopy can extract the curve of spectral gain from its parametric superfluorescence. This unique spectrum correction method...Femtosecond time-resolved fluorescence non-collinear optical parametric amplification spec- troscopy can extract the curve of spectral gain from its parametric superfluorescence. This unique spectrum correction method enables fluorescence non-collinear optical parametric amplification spectroscopy acquiring the genuine transient fluorescence spectrum of the studied system. In this work we employ fluorescence non-collinear optical parametric amplification spectroscopy technique to study the solvation dynamics of DCM dye in ethanol solution, and confirm that genuine solvation correlation function and shift of peak frequency can be derived from transient fluorescence spectra after the spectral gain correction. It demonstrates that fluorescence non-collinear optical parametric amplification spectroscopy can benefit the research fields, which focuses on both fluorescence intensity dynamics and fluorescence spectral shape evolution.展开更多
Time-and frequency-resolved broadband transient grating(BB-TG) spectroscopy is used to distinguish between ground-and excite-electronic state vibrational coherence at different wavelengths. Qualitative theoretical ana...Time-and frequency-resolved broadband transient grating(BB-TG) spectroscopy is used to distinguish between ground-and excite-electronic state vibrational coherence at different wavelengths. Qualitative theoretical analysis using double-sided Feynman diagrams indicates that a superposition of ground and excited state vibrational coherence are contained in the ground state absorption(GSA) and stimulated emission(SE) overlap band, while only the excited state is contained in the excited state absorption(ESA) band. The TG experiment, in which a white light continuum(WLC) is adopted as a probe, is conducted with rhodamine101(Rh101~+) as the target molecule. Fourier analysis of TG dynamics in a positive delay time range at specific wavelengths enables us to distinguish the low-frequency vibrational modes of Rh101 in ground-and excite-electronic states.展开更多
奇异值分解(Singular value decomposition,SVD)作为一种有效的信号降噪方法广泛应用于旋转机械振动信号周期性瞬态冲击提取中。传统SVD以能量为导向,无法提取出能量较弱但含故障信息丰富的奇异分量(Singular Component,SC)。为此,提出...奇异值分解(Singular value decomposition,SVD)作为一种有效的信号降噪方法广泛应用于旋转机械振动信号周期性瞬态冲击提取中。传统SVD以能量为导向,无法提取出能量较弱但含故障信息丰富的奇异分量(Singular Component,SC)。为此,提出加权firm阈值奇异值分解(Weighted Firm Singular Value Decomposition,WFSVD)方法。该方法首先引入平方包络谱峭度(Squared Envelope Spectrum Kurtosis,SESK)作为量化故障敏感度的指标,以评估各个SC所含故障信息的丰富程度;其次,将SESK作为权重因子引入到基于firm阈值的SC去噪中,设计基于SESK的加权firm阈值SC去噪策略;最后,重构信号,实现信号降噪并有效提取故障特征。对于仿真信号与试验数据的分析验证了所提方法在周期性微弱瞬态冲击提取及旋转机械故障诊断中的有效性。展开更多
文摘Femtosecond time-resolved fluorescence non-collinear optical parametric amplification spec- troscopy can extract the curve of spectral gain from its parametric superfluorescence. This unique spectrum correction method enables fluorescence non-collinear optical parametric amplification spectroscopy acquiring the genuine transient fluorescence spectrum of the studied system. In this work we employ fluorescence non-collinear optical parametric amplification spectroscopy technique to study the solvation dynamics of DCM dye in ethanol solution, and confirm that genuine solvation correlation function and shift of peak frequency can be derived from transient fluorescence spectra after the spectral gain correction. It demonstrates that fluorescence non-collinear optical parametric amplification spectroscopy can benefit the research fields, which focuses on both fluorescence intensity dynamics and fluorescence spectral shape evolution.
基金Project supported by the Science Challenge Project,China(Grant No.TZ2016001)the National Natural Science Foundation of China(Grant No.21673211)
文摘Time-and frequency-resolved broadband transient grating(BB-TG) spectroscopy is used to distinguish between ground-and excite-electronic state vibrational coherence at different wavelengths. Qualitative theoretical analysis using double-sided Feynman diagrams indicates that a superposition of ground and excited state vibrational coherence are contained in the ground state absorption(GSA) and stimulated emission(SE) overlap band, while only the excited state is contained in the excited state absorption(ESA) band. The TG experiment, in which a white light continuum(WLC) is adopted as a probe, is conducted with rhodamine101(Rh101~+) as the target molecule. Fourier analysis of TG dynamics in a positive delay time range at specific wavelengths enables us to distinguish the low-frequency vibrational modes of Rh101 in ground-and excite-electronic states.
