Transitions between Rydberg States of Na in an Electric Field Induced by Blackbody Radiation

Abstract

It is well known that blackbody radiation (BBR) has an important effect on Rydberg atoms.¹ Past work on this problem has been limited to field free states, and has concentrated on understanding the main effect of BBR, namely the redistribution of population between Rydberg states. More recently our group has studied the extent to which multistep transitions occur.² These studies are important because the effects of BBR are ubiquitous to any Rydberg atom experiment that is not performed in low-temperature surroundings. The same problem but in the presence of an external static electric field poses new interesting questions that test our understanding of the structure and dynamics of Rydberg atoms in external fields. If we populate a given Stark state and let BBR induce transitions to neighboring states there are two extreme situations that we might expect. In the case of H, transition matrix elements between Rydberg Stark states are non-negligible only when the parabolic quantum numbers of the states (n ₁ or n ₂) change by an amount equal to the change in the principal quantum number for the transition (e.g., [n,n ₁,n ₂,m]→[n ± p,n ₁ ± p,n ₂,m] if n ₁ > n ₂ and →[n ± p,n ₁,n ₂ ±p,m] if n ₁ < n ₂)_. ^3,4 Therefore, for H we expect population transfers to one or two states of each n-manifold. In contrast, low-m alkali atoms may suffer from such heavy state mixing and their structure may depart so much from that of H⁵ that we might expect a more diffusive and less discrete population redistribution. In this work we study BBR-induced population transfers in low-m states of Na.