Hello Fatima Zohra Dahmani,

Attached herewith Research Article links that will help you to understand the difference between Hydrogen atoms in Plasma CVD and Hydrogen atoms in Hot Wire CVD (Catalytic CVD or initiated CVD).

01. Article Cat-CVD (hot-wire CVD): how different from PECVD in preparin...

02. Article Characteristics of the hot-wire CVD reactor on aSi:H deposition

03. Article Industrialization of Hot Wire Chemical Vapor Deposition for ...

04. Article ChemInform Abstract: Hot Wire Chemical Vapor Deposition Chem...

I hope I have answered your question.

With Best Wishes,

Samir G. Pandya

Hello Mr Samir G Pandya

Thank you for answering my question, but i already checked those documents. my question is more precised (please check @)

As i mentioned in question, what makes that ....."Optical emission measurements are convenient but this technique cannot be applied to catalytic decomposition because it does not produce electronically excited species." [Takashi MORIMOTO, Japanese Journal of Applied Physics Vol. 44, No. 1B, 2005, pp. 732–735]

@ Production and Detection of H Atoms and Vibrationally Excited H2 Molecules in CVD Processes**

By Hironobu Umemoto*

DOI: 10.1002/cvde.201000043

I'd recommend to consider difference in mechanisms of excitation.

In plasma dissociation H2 molecule (or any other molecule with H atoms) decomposes due to electron impact - full energy of system is (significantly) higher than potential barrier. After dissociation excessive energy is distributed between kinetic energy and internal energy of products. In the case of neutral H internal energy is electron excitation and this energy will simultaneously release in spontaneous radiation. This radiation may be registered to get information on intermediate excited state of H atoms and their number.

In the case of catalytic decomposition process does not require energy higher than barrier(though initial vibrational energy should be high enough in comparison with potential energy after barrier) i.e. resulting energy of system is lower than barrier and energy excess is distributed only between kinetic energies of products and vibrational degrees of freedom of molecules(if any polyatomic species are possible in products).