Intense, directional UV emission from molecular nitrogen ions in an adaptively controlled femtosecond filamentG. Andriukaitis, J. Möhring, D. Kartashov, A. Pugžlys, A. Zheltikov, M. Motzkus and A. BaltuškaEPJ Web of Conferences, 41 (2013) 10004DOI: https://doi.org/10.1051/epjconf/20134110004