The photophysics and photochemistry of thioacetamide (CH3CSNH2) after excitation to the S2 electronic state were investigated by using resonance Raman spectroscopy in conjunction with the complete active space self-consistent field (CASSCF) method and density functional theory (DFT) calculations. The A-band resonance Raman spectra in acetonitrile, methanol, and water were obtained at 299.1, 282.4, 266.0, 252.7, and 245.9 nm excitation wavelengths to probe the structural dynamics of thioacetamide in the S2 state. CASSCF calculations were done to determine the transition energies and structures of the lower-lying excited states, the conical intersection points CI(S2/S1) and CI(S1/S0), and intersystem crossing points. The structural dynamics of thioacetamide in the S2 state was revealed to be along eight Franck–Condon active vibrational modes ν15, ν11, ν14, ν10, ν8, ν12, ν18, and ν19, mostly in the CC/CS/CN stretches and the CNH8,9/CCH5,6,7/CCN/CCS in-plane bends as indicated by the corresponding normal mode descriptions. The S2 → S1 decay process via the S2/S1 conical intersection point as the major channel were excluded. The thione–thiol photoisomerization reaction mechanism of thioacetamide via the S2,FC → S′1,min excited state proton transfer (ESPT) reaction channel was proposed.

The resonance Raman spectroscopic study of the excited state structural dynamics of 1,3-dimethyluracil (DMU), 5-bromo-1,3-dimethyluracil (5BrDMU), uracil, and thymine in water and acetonitrile were reported. Density functional theory calculations were carried out to help elucidate the ultraviolet electronic transitions associated with the A-, and B-band absorptions and the vibrational assignments of the resonance Raman spectra. The effect of the methylation at N1, N3 and C5 sites of pyrimidine ring on the structural dynamics of uracils in different solvents were explored on the basis of the resonance Raman intensity patterns. The relative resonance Raman intensities of DMU and 5BrDMU are computed at the B3LYP-TD level. Huge discrepancies between the experimental resonance Raman intensities and the B3LYP-TD predicted ones were observed. The underlying mechanism was briefly discussed. The decay channel through the S1(1nπ*)/S2(1ππ*) conical intersection and the S1(1nπ*)/T1(3ππ*) intersystem crossing were revealed by using the CASSCF(8,7)/6-31G(d) level of theory calculations.

FT-Raman and/or FT-IR spectra of 3-amino-2-cyclohexen-1-one (ACyO) in solid state and/or in solvents of water and acetonitrile were obtained. Density functional theory calculations were done to help elucidate the vibrational band assignments. The A-band resonance Raman spectra of ACyO were acquired in water and acetonitrile solvents to examine the excited state structural dynamics and the state-mixing or curve-crossing tuned by solvents. A preliminary resonance Raman intensity analysis using the time-dependent wave-packet theory and simple model was done for ACyO in acetonitrile solvent. Resonance Raman spectroscopic probing of the excited state curve-crossing or state-mixing was proposed.Graphical abstractHighlights► The vibrational assignments of 3-amino-2-cyclohexen-1-one were carried out. ► The Franck–Condon region structural dynamics were obtained. ► The absorption spectrum and absolute resonance Raman cross-sections were simulated. ► Modulation of Sπ/Sn vibronic coupling or curve crossing by solvents was studied.

Various extraordinary textiles were excavated from a graveyard at Yingpan, Xinjiang, on the middle route of the ancient Silk Road. Applications of western motifs and designs to traditional Chinese textiles led to the emergence of compound woven textiles with central Asian characters. For a better understanding of the cultural exchanges and textile trade between the West and the East in ancient times, identifications of archaeological fibres and dyes were carried out for various funerary textile objects by using multiple analytical techniques, such as high performance liquid chromatography with photodiode detection, optical microscopy, scanning electronic microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). Fibre identifications were performed for 35 archaeological textile samples, and the results showed that the ancient textiles were mostly made from Bombyx mori silk and wool. The SEM and FT-IR experimental results revealed that these ancient textiles remained morphologically intact due to the special (very dry) climate in Xinjiang, but noticeably degraded at the molecular level due to long time thermo-ageing and/or biodegradation. The principal colouring matters, such as alizarin, purpurin, indigotin and luteolin, were respectively characterised for nine archaeological textile samples. The yellow dyestuffs derived from luteolin-based plants were assumed to have been imported to China from the Middle East and Western Asia through the Silk Road.Highlights► Fibre and dye identifications were achieved for archaeological textiles from Xinjiang. ► Most of the ancient textiles were made from B. mori silk and wool. ► The ancient silk textiles were intact in morphology but degraded at the molecular level. ► The major components of the dyestuffs were alizarin, purpurin, indigotin and luteolin. ► Some yellow dyestuffs were imported to China from Middle East or Western Asia.

The resonance Raman spectra were obtained for both 2-thiopyridone (2TP) and its proton-transfer tautomer 2-mercaptopyridine (2MP) in water solution. Density functional theory (DFT) calculations were carried out to help elucidate their ultraviolet electronic transitions and vibrational assignments of the resonance Raman spectra associated with their B-band absorptions. The nanosecond time-resolved resonance Raman spectroscopic experiment was carried out to further confirm the assignment that the transient species was the ground state 2MP. The different short-time structural dynamics were examined for both 2TP and 2MP in terms of their resonance Raman intensity patterns. The transition barriers between 2TP and 2MP for S0, T1, and S1 states are determined by using (U)B3LYP-TD and CASSCF level of theory computations, respectively. The excited state proton transfer (ESPT) reaction mechanism is proposed and briefly discussed.