  The single-particle superconducting Green's functions of a Luther-Emery
liquid is computed by bosonization techniques. Using a formulation introduced
by Poilblanc and Scalapino [Phys. Rev. B v. 66, art. 052513 (2002)], an
asymptotic expression of the superconducting gap is deduced in the long
wavelength and small frequency limit. Due to superconducting phase
fluctuations, the gap exhibits as a function of size L a (1/L)^{1/2K_\rho}
power-law decay as well as an interesting singularity at the spectral gap
energy. Similarities and differences with the 2-leg t-J ladder are outlined.
