Laser-induced- and dispersed-fluorescence studies of rhodamine 590 and 640 ions formed by electrospray ionization: Observation of fluorescence from highly-excited vibrational levels of S1 states.
Laser-induced- and dispersed-fluorescence studies of rhodamine 590 and 640 ions formed by electrospray ionization: Observation of fluorescence from highly-excited vibrational levels of S1 states.
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通过电喷雾电离形成的罗丹明 590 和 640 离子的激光诱导和分散荧光研究：从 S1 态的高激发振动能级观察荧光。
DOI：
10.1039/c8cp04067b
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Kenji Honma
中科院分区：
文献类型：
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作者：
間 紗希子・宮武 秀行・内田 朗・細井 晴子;Kenji Honma
用一种新的仪器研究了罗丹明590(R590)和罗丹明640(R640)阳离子的气相荧光激发和发射性质，该仪器允许将光激发扩展到紫外区。离子是由电喷雾离子源产生的，解溶的离子积累在室温四极离子陷阱中。除了观察到这两种染料众所周知的S1-S0转变外，还观察到了R590的两个紫外线(UV)带(以前没有报道过)。与观察到的染料在甲醇溶液中的转变相比，气相中的S1-S0转变向明显更高的能量移动。这些位移表明，这两种染料的S1态比S0态更容易被有利的溶剂相互作用稳定。观察到的R590的UV谱带归属于高能S3和Sn态的跃迁。紫外光激发得到的df光谱与s1激发时记录到的光谱相似，但紫外光激发后的发射略向红区移动。这些观测结果与S3或Sn的快速内转换形成的S1态的高振动能级的发射是一致的。在真空中，没有碰撞延长了振动激发的S1态的寿命，从而允许观察到来自这些态的荧光。在R640的紫外激发下也观察到了类似的DF光谱，这表明来自振动热S1态的荧光是气相离子的普遍现象。
The gas-phase fluorescence excitation and emission properties of rhodamine 590 (R590) and rhodamine 640 (R640) cations were studied using a novel instrument that allows extension of optical excitation to the UV region. Ions were generated by an electrospray ion source, and desolvated ions were accumulated in a room-temperature quadrupole ion-trap. In addition to the well-known S1–S0 transition observed for both dyes, two ultraviolet (UV) bands (that have not been reported previously) were observed for R590. When compared with transitions observed for the dyes in methanol solutions, the S1–S0 transitions in the gas phase are shifted to significantly higher energies. These shifts suggest that the S1 states for both dyes are more stabilized by favorable solvent interactions than the S0 states. The UV bands observed for R590 were assigned to the transitions involving the higher-energy S3 and Sn states. The DF spectra obtained upon UV excitation are similar to those recorded for S1 excitation; however, the emission after UV excitation is shifted slightly to the red region. These observations are consistent with the emission from high-vibrational levels of the S1 state formed upon fast internal conversion from S3 or Sn. In vacuo, the absence of collisions extends the lifetimes of vibrationally-excited S1 states, allowing fluorescence from these states to be observed. A similar DF spectrum was also observed for the UV excitation of R640, suggesting that fluorescence from vibrationally hot S1 states is a general phenomenon for ions in the gas phase.