Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
Philos Trans A Math Phys Eng Sci. 2012 Nov 13;370(1978):5028-40. doi: 10.1098/rsta.2012.0017.
We report on the recent observation of new spectral lines of cold H(3)(+) ions lying well in the visible spectral region. Transitions from the two lowest ro-vibrational levels to final levels up to 16,700 cm(-1), almost half way to the dissociation limit, have been measured, involving up to eight vibrational quanta. The observed transitions are more than six orders of magnitude less intense than the v(2)(1) fundamental band and yet another order of magnitude weaker than reached by previous sensitive action spectroscopy in the near-infrared region. The measurements were carried out in a cryogenic 22-pole ion trap with H(3)(+) ions cooled to their lowest rotational levels by helium buffer gas. Laser-induced chemical reactions lead to the formation of ArH(+) ions detected with single-ion sensitivity. These visible measurements, together with the previous near-infrared measurements, have helped to further develop empirically corrected calculations and have provided essential benchmarks for new ab initio calculations that now reach a spectroscopic accuracy of 0.1 cm(-1) on average up to the highest observed transition. Highly sensitive action spectroscopy and the attained high-accuracy predictions will enable us to find and measure transitions even further into the visible region of H(3)(+), paving the way towards the dissociation limit.
我们报告了最近观察到的冷 H(3)(+)离子的新光谱线，这些谱线位于可见光谱区域内。我们测量了从两个最低的振转能级到最终能级的跃迁，最终能级高达 16700cm(-1)，几乎达到了离解极限的一半，涉及到多达八个振动量子。与 v(2)(1)基频带相比，观察到的跃迁强度要低六个数量级以上，与之前在近红外区域进行的灵敏动作光谱学测量相比，强度也要低一个数量级。测量是在一个低温 22 极离子阱中进行的，H(3)(+)离子被氦缓冲气体冷却到最低旋转能级。激光诱导的化学反应导致 ArH(+)离子的形成，这些离子被单离子灵敏度检测到。这些可见测量，以及之前的近红外测量，有助于进一步发展经验修正计算，并为新的从头计算提供了必要的基准，这些计算现在在平均高达最高观察到的跃迁的 0.1cm(-1)的光谱精度。高灵敏度动作光谱学和达到的高精度预测将使我们能够发现和测量更远的 H(3)(+)可见区域的跃迁，为达到离解极限铺平道路。
