Dipole-phase evolution of laser-dressed autoionizing states in neon

We present theoretical attosecond transient absorption spectroscopy calculations of neon, focusing on the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:mrow> <a:mo>[</a:mo> <a:mi>He</a:mi> <a:mo>]</a:mo> </a:mrow> <a:mspace width="0.28em"/> <a:mn>2</a:mn> <a:mi>s</a:mi> <a:mn>2</a:mn> <a:msup> <a:mrow> <a:mi>p</a:mi> </a:mrow> <a:mn>6</a:mn> </a:msup> <a:mn>3</a:mn> <a:mi>p</a:mi> <a:mspace width="0.16em"/> <a:msup> <a:mrow/> <a:mn>1</a:mn> </a:msup> <a:mi>P</a:mi> <a:msup> <a:mrow/> <a:mo>∘</a:mo> </a:msup> </a:mrow> </a:math> autoionizing state, in an extreme ultraviolet pump, near infrared probe configuration. We find that as the two laser pulses overlap, there is a strong shift in the dipole phase, which we attribute to an effective reduction in the coupling strength between the bound and continuum states as the near infrared pulse makes new pathways accessible. To quantitatively analyze the dipole phase in the presence of perturbed free-induction decay, we demonstrate a method to obtain resonance phase and strength values directly from the dipole spectrum.