## 4 Conclusions  
We calculated time-resolved photoelectron spectra for photoemission from solid surfaces in a one-dimensional single-active-electron model using jellium-type potential and electron-hole interaction. Thus, a band structure does not exist in this model. For RABBITT and streaking spectra, we applied the same IR field strength of 1 V/nm, i.e., \(1.3\times 10^{11}\) W/cm\({}^{2}\) peak intensity, at a pulse duration of 5 fs. Both methods yielded analyzable signals. This corresponds to a streaking amplitude of 1.2 eV at \(E_{\rm kin}=25\) eV and to a streaking amplitude of 1.7 eV at \(E_{\rm kin}=50\) eV, which is comparable to typical results for streaking at solid surfaces [9; 10; 11; 39]. IR intensity applied in the RABBITT experiments was in the same order of magnitude [23; 32; 40].  
We could show for solid surfaces that RABBITT and streaking yield identical delay information within evaluation accuracy. Analysis revealed that differences between these techniques are expected to play a role only for photoelectrons with kinetic energy below 10 eV in the investigated system. In core-level photoemission spectra from solid samples, photoelectrons in this kinetic energy range are impossible to determine in practice because these photoemission peaks would be covered by a strong secondary electron background. Based on our analysis, differences between RABBITT and streaking delays determined at surfaces with vanishing internal IR field in an accessible energy range are smaller than \(\pm 3\) as. Obviously, this is also valid for delay differences.  
For experimental proof of our model calculations, van der Waals crystals might be a suitable set of samples, because streaking delays of WSe\({}_{2}\) photoemission spectra were successfully explained by the model applied here using jellium-type potential and including electron-holeinteraction for electron transport while treating angular momentum influences as intra-atomic effects. Additionally, they exhibited stable surface conditions, which is helpful for such a challenging experiment [10].  
Moreover, it can be stated that both streaking and RABBITT delay reflect photoemission time within our model for sufficiently high kinetic energy as long as the IR field inside the material can be neglected.  
In a system described by homogeneous inner potential, i.e., a jellium model, the EUV transition matrix element is a rather flat function with respect to energy. However, if the EUV transition matrix element in a system exhibits narrow features, photoelectron yield at narrow harmonic lines is sensitive to these features in a RABBITT measurement. This could lead to asymmetric spectral distributions. In a streaking spectrogram, broad energy distribution might average out these features, and the method might be less sensitive to transition matrix properties, and differences to RABBITT could arise. So, for more advanced models of solid-state photoemission, taking, for example, band-structure effects into account, deviations between RABBITT and streaking spectroscopy might appear. Hence, similar investigations as are needed for a more advanced description of electron dynamics in solids.  
Formal analysis, A.G.; funding acquisition, M.A. and W.P.; investigation, A.G.; project administration, W.P.; software, A.G.; supervision, M.A. and W.P.; validation, A.G. and S.N.; writing--original draft, A.G.; writing--review and editing, A.G., S.N., W.E., B.S., M.A., and W.P.  
This research was funded by the German Research Foundation within Priority Program SPP \"Quantum Dynamics in Tailored Intense Fields\" (grant number PF317/10-1).  
The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; and in the decision to publish the results.