Raman spectroscopy on the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>β</mml:mi><mml:mo>−</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">N</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>structure formed by low-energy nitrogen ion implantation into a diamond surface

Raman spectroscopy was employed to study the structure of the carbon nitride formed by low-energy nitrogen ion implantation into a diamond film. A series of narrow Raman peaks were observed in the range of 150--1500 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$. These peaks match well with the calculated Raman frequencies of $\ensuremath{\beta}\ensuremath{-}{\mathrm{C}}_{3}{\mathrm{N}}_{4},$ revealing the formation of the $\ensuremath{\beta}\ensuremath{-}{\mathrm{C}}_{3}{\mathrm{N}}_{4}$ phase. No Raman peaks were detected in this region when a graphite substrate was implanted under the same conditions, suggesting that the ${\mathrm{sp}}^{3}$-bonded carbon favors the formation of the ${\mathrm{sp}}^{3}$-bonded $\ensuremath{\beta}\ensuremath{-}{\mathrm{C}}_{3}{\mathrm{N}}_{4}.$