In a high-resolution laser spectroscopic study, using a tunable Fourier-transform limited light source in the extreme ultraviolet, the b (1)Pi(u) excited valence state of molecular nitrogen is reinvestigated for vibrational levels v = 1, 4, 5, and 6. From line broadening of individual rotational levels excited state lifetimes were determined: tau((v=1)) = 1.1 +/-0.3 ns, tau((v=4)) = 18 +/- 1 ps, tau((v=5)) = 205 +/- 25 ps, and tau((v=6)) = 350 +/- 75 ps. Additionally, the lifetime of the o(3) (1)Pi(u), v=0 Rydberg state was determined: tau = 240 +/- 50 ps. For the b (1)Pi(u), v = 1 state improved rotational constants were determined. (C) 2000 American Institute of Physics. [S0021-9606(00)02113-9].