Spectral Data for Finite Volume Hyperbolic Surfaces at the Bottom of the Continuous Spectrum

The spectrum of the Laplace operator on finite area non-compact surfaces becomes stable if one adjoins to the L2 eigenvalues the scattering frequencies. For the bottom of the continuous spectrum (14) we need to take into account any non-vanishing Eisenstein series at s = 12. In this work the particular behaviour of the spectrum at 14 is studied with respect to genericity of L2 eigenvalues and of non-vanishing Eisenstein series at s = 12.