Photoionization of KCs Molecule: Origin of the Structured Continuum?

Goran Pichler,David Sarkisyan,Jahja Kokaj,Joseph Mathew,Robert Beuc,Nimmy Jose

doi:10.3390/atoms8020024

Goran Pichler, David Sarkisyan + Show 4 more

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https://doi.org/10.3390/atoms8020024

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Abstract

We report the experimental observation of photoionization bands of the KCs molecule in the deep ultraviolet spectral region between 200 and 420 nm. We discuss the origin of observed photoionization bands as stemming from the absorption from the ground state of the KCs molecule to the excited states of KCs+ molecule for which we used existing potential curves of the KCs+ molecule. An alternative explanation relies on the absorption from the ground state of the KCs molecule to the doubly excited states of the KCs** molecule, situated above the lowest molecular state of KCs+. The relevant potential curves of KCs** are not known yet, but all those KCs** potential curves are certainly autoionizing. However, these two photoionization pathways may interfere resulting in a special interference structured continuum, which is observed as complex bands.

Highlights

High-temperature alkali mixtures possessing high densities of constituents enable observation of the characteristic bands of mixed alkali molecules [1]
the side-arm finger (Tf) low-resolution part of the spectrum, low resolution is justified temperatures measured at the top of the vertical side-arm
Experimental observation of the eight photoionization bands of the KCs molecule in the deep ultraviolet spectral region presents a challenge for the future quantum-mechanical calculations

Summary

Introduction

High-temperature alkali mixtures possessing high densities of constituents enable observation of the characteristic bands of mixed alkali molecules [1]. Heavy alkali heteronuclear molecules are interesting because they have a permanent dipole moment which enables many applications like orientation in an external electric field and quantum computing. The KCs molecule, with a permanent dipole moment of 1.92 Debye, has been extensively studied by several research groups using high-resolution spectroscopy techniques. The lower excited states with asymptotes at K(4s) + Cs(6p) and/or K(4p) + Cs(6s) were usually the goals of several groups [2,3]. Some of the KCs intermediate high excited states were investigated [4,5], of which the E state has a shelf-like shape. Even the formation of ultracold polar ground state KCs molecules via an optical process has been discussed in [6]

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