Title: Interpreting pulse-shape effects in pump-probe spectroscopies
Author(s):

	A.M. Shvaika (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine) ,
	O.P. Matveev (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine) ,
	T.P. Devereaux (Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA; Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA) ,
	J.K. Freericks (Department of Physics, Georgetown University, 37th and O Streets, NW, Washington, DC 20057, USA)

The effect of the pulse-shape on pump-probe spectroscopies is examined for the simplest model of noninteracting fermions on an infinite-dimensional hypercubic lattice. The probe-modified density of states follows the time evolution of the pump and displays narrowing and Floquet-like sidebands at the pump maximum, whereas the photoelectron spectra are also strongly affected by the nonequilibrium occupation of the single-particle states due to the excitation from the pump. The nonequilibrium Raman cross section is derived, and the nonresonant one in both the A_1g and B_1g symmetries contains a number of peaks at the pump maximum, which can be attributed to an interference effect or Brillouin scattering off the time variations of the stress tensor. Both the "measured" occupation of single-particle states and the ratio of Stokes to anti-Stokes peaks are strongly modified by the probe-pulse width, which must be included in the interpretation of experimental results.

Key words: pump-probe spectroscopy, photoelectron spectroscopy, electronic Raman scattering, nonequilibrium Green's function
PACS: 78.47.J-, 79.60.-i, 78.30.-j, 71.10.Fd

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