Validity of extracting photoionization time delay from the first moment of streaking spectrogram<xref rid="cpb_28_1_013201fn1" ref-type="fn">*</xref><fn id="cpb_28_1_013201fn1"><label>*</label><p>Project supported by the Talent Introduction Foundation of Qiannan Normal University of Nationalities, China (Grant No. qnsyrc201619), Natural Science Foundation of Guizhou Provincial Education Department for Young Talents, China (Grant No. Qian Education Contract KY[2017]339), and Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy (Grant No. DE-FG02-86ER13491).</p></fn>

Validity of extracting photoionization time delay from the first moment of streaking spectrogram**

Project supported by the Talent Introduction Foundation of Qiannan Normal University of Nationalities, China (Grant No. qnsyrc201619), Natural Science Foundation of Guizhou Provincial Education Department for Young Talents, China (Grant No. Qian Education Contract KY[2017]339), and Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy (Grant No. DE-FG02-86ER13491).

Wei Chang-Li¹, Zhao Xi^{2, †}

(a) XUV spectral intensity U²(Ω). (b) XUV spectral phase Φ(Ω) for a TL pulse (GDD^XUV = 0, Δt = 197 as) and a chirped pulse (GDD^XUV = 2.57 × 10⁴ as², Δt = 410 as). (c) XUV group delay τ^XUV(Ω). (d) The electric field E_IR(t) and vector potential −A(t) of the IR field.