Dear Vishal, your spectra resemble a completely contaminated sample, mostly by hydro-carbons and water. The two humps are due to the secondary cut off, may be shifted by some charging. Try to heat the sample to clean it. contact the surfce of the sample by an gold wire and measur spectra in the vicinity of the contact. In addition you may take spectra of the valence band by monochromated XPS.

dear Vishal, also be careful with the linear functions you have fitted to your data, the intersection to the x-axis are dangerous! And I agree with what Christian Pettenkofer - the double-peaked cut-off at low kinetic energy is (more or less) certainly due to charging. This might be because of the nature of the sample (LaMnO3 is only poorly conducting) or because of a poor electrical connection of your sample to the ground. Also it appears that the energy zero of your system is eventually not correctly calibrated (or set) - I cannot see a Fermi level ...

Good luck in any case, Dirk

Thanks Christian Pettenkofer and Dirk Luetzenkirchen-Hecht . I understood that the peaks at higher B.E are from the contamination (water and hydrocarbons) and also from charging.

1. Dirk, by looking at the spectrum, how can we find that the system is not calibrated? Where do I need to see?

2. It looks like I have done mistake in fitting. I should have taken a baseline first and then intersection of this with the liner fit might give me the correct results. In here I do it then the VBM is coming at 4.65eV.

Do you think I am going in right direction? (By the way, I didn't do any linear fit. Just I drew a possible/suitable line.)

Dear Vishal, it seems that the position of the Fermi level was taken from a metallic reference, however, if your sample is charged (as one may assume because of the double-peaked structure of the secondary cut-off, your Fermi level may be shifted as well. And I feel that 3.2 eV is a bit too small in work function for LaMnO3 - right? If I interpolate the first peak in the cut-off to zero (see attachment), then a WF of about 4.4 eV results, which I feel would be a more realistic value - do you agree?

Best regards, Dirk

Hello Vishal, I agree with Christian Pettenkofer's comment that your sample surface seems to be contaminated or have energetically different species, contributing to the double onset. You may be interested in the following papers where we studied the sample heterogeneity/double SE cutoff in detail.

1) Article Invisible High Workfunction Materials on Heterogeneous Surfaces

2)Article Nanoscale Heterogeniety and Workfunction Variations in ZnO Thin films