As a chemist, I can provide you with some general information, but I cannot give you a specific rate constant for non-radiative deactivation of the excited state of a given small organic molecule without more information about the molecule in question.The rate constant for non-radiative deactivation, also known as internal conversion or intersystem crossing, depends on several factors, including the specific molecule, its electronic structure, and the surrounding environment. Ab initio calculations, which are computational methods based on quantum mechanics, can be used to determine the rate constant for a specific molecule. However, these calculations can be complex and computationally demanding, and the results may vary depending on the level of theory and basis set used.To obtain the rate constant for non-radiative deactivation of a specific molecule, you would need to perform ab initio calculations using appropriate software and input parameters, or consult the scientific literature for previously published results on that molecule.