  The performance of Superconducting radio frequency cavities (SRF) is strongly
influenced by various impurities within the penetration depth (~50nm) of Nb,
which in turn depends on the applied surface treatments. The effect of these
surface treatments on the impurities of Nb has been explored using various
surface analytical treatments. But, the results are still inadequate in many
aspects and the effect of sequential SRF treatments on the impurity
distribution has not been explored. The present study analyses various
impurities within the penetration depth of Nb samples, treated by SRF cavity
processing techniques like colloidal silica polishing (simulating centrifugal
barrel polishing), buffer chemical polishing (BCP), high pressure rinsing (HPR)
and degassing under high vacuum (HV) condition at 600{\deg}C for 10hrs. Static,
dynamic and slow sputtering modes of Time of flight secondary ion mass
spectrometry (TOFSIMS) technique was employed to study the effect of the above
treatments on interstitial impurities, hydrocarbons, oxides, acidic residuals,
reaction products and metallic contaminations. The study confirms that the
impurity distribution in Nb is not only sensitive to the surface treatment, but
also to their sequence. Varying the treatment sequence prior to HV degassing
treatments affected the final impurity levels in HV degassed bulk Nb samples.
BCP treated samples, exhibited minimum hydrocarbon and metallic contamination
but, led to extensive contamination of the oxide layer with residuals and
reaction products of acids used in BCP solution. HPR treatment, on the other
hand was effective in reducing the acidic impurities on the top surface. The
study also establishes the application of TOFSIMS technique to analyze and
evolve SRF treatments.
