def Ecmrel2Enm(Ecmrel, ref_wavelength=515):
    """Converts energy from cm-1 relative to a ref wavelength to an energy in wavelength (nm)

    Parameters
    ----------
    Ecmrel: float
            photon energy in cm-1
    ref_wavelength: float
                    reference wavelength in nm from which calculate the photon relative energy

    Returns
    -------
    float
         photon energy in nm

    Examples
    --------
    >>> Ecmrel2Enm(500, 515)
    528.6117526302285
    """
    Ecm = 1 / (ref_wavelength * 1e-7) - Ecmrel
    return 1 / (Ecm * 1e-7)