The wavelength dependence of electron localization of H2+ and its isotopomers in the ultraviolet pump-probe scheme is investigated by numerically solving the time-dependent Schr(o)dinger equation.By combining with a semiclassical method,an effective analytical formula expressed in the adiabatic representation is established to describe the localization probability with several zero crossings.A stable zone with respect to the laser intensity and carrier envelope phase is found at a relatively long probe wavelength.Finally,the critical probe wavelengths to reach at the stable zone are derived by using the three-dimensional model.Slower nuclear motion of heavier isotopomers leads to a longer critical wavelength.