Two-pulse field-free orientation reveals anisotropy of molecular shape resonance Kraus, P. M. Baykusheva, Denitsa Rangelova Wörner, H. J. General Physics and Astronomy We report the observation of macroscopic field-free orientation, i.e., more than 73% of CO molecules pointing in the same direction. This is achieved through an all-optical scheme operating at high particle densities (>10(17)  cm(-3)) that combines one-color (ω) and two-color (ω+2ω) nonresonant femtosecond laser pulses. We show that the achieved orientation solely relies on the hyperpolarizability interaction as opposed to an ionization-depletion mechanism, thus, opening a wide range of applications. The achieved strong orientation enables us to reveal the molecular-frame anisotropies of the photorecombination amplitudes and phases caused by a shape resonance. The resonance appears as a local maximum in the even-harmonic emission around 28 eV. In contrast, the odd-harmonic emission is suppressed in this spectral region through the combined effects of an asymmetric photorecombination phase and a subcycle Stark effect, generic for polar molecules, that we experimentally identify. American Physical Society 2014 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/14020 Kraus PM, Baykusheva DR, Wörner HJ. Two-pulse field-free orientation reveals anisotropy of molecular shape resonance. <i>Physical Review Letters</i>. 2014;113(2). doi:<a href="https://doi.org/10.1103/physrevlett.113.023001">10.1103/physrevlett.113.023001</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1103/physrevlett.113.023001 info:eu-repo/semantics/altIdentifier/issn/0031-9007 info:eu-repo/semantics/altIdentifier/e-issn/1079-7114 info:eu-repo/semantics/altIdentifier/arxiv/1311.3923 info:eu-repo/semantics/altIdentifier/pmid/25062172 info:eu-repo/semantics/openAccess