  The present work reports results of the semi-empirical determination of the
spontaneous emission transition probabilities (Einstein coefficients) for
Q-branch lines of Fulcher-$\alpha$ band system and radiative lifetimes of upper
electronic-vibro-rotational (rovibronic) levels for the most important
isotopologues of diatomic hydrogen. They are based on an adiabatic theoretical
model and all currently available experimental data on rovibronic energy
levels, ratios of the line strengths and the lifetimes. Numerical data are
presented in tabular format for vibrational quantum numbers v=0-7 (N is the
quantum number of total angular momentum of the molecule excluding electron and
nuclear spins). The uncertainties (one SD) of experimental and semi-empirical
data are listed for each datum. Currently available results of ab initio
calculations are listed and may be used for comparisons. For the
$d^3\Pi_u^-$,v=4-6,N=1 levels of the $H_2$ molecule the lifetimes caused by
predissociation via non-adiabatic interaction with continuum of the
$c^3\Pi_u^-$ electronic state were estimated for the first time in the basis of
experimental and semiempirical data.
