## 3 Results and Discussion
### X-ray Photoelectron Spectroscopy (XPS)  
X-ray photoelectron spectroscopy was applied to evaluate the surface composition of the LPArP-treated BC. Analysis of the XPS spectra indicated only the presence of oxygen and carbon on the surfaces of the samples. The ratio of oxygen atoms to carbon atoms on the surfaces of the studied materials was determined from the atomic concentration of these elements, which was calculated from the intensity of the XPS signals: O 1s and C 1s (Table 2). The calculations assumed a homogeneous distribution of oxygen and carbon atoms in the surface layer. Considering the formula of cellulose as (C\({}_{6}\)H\({}_{10}\)O\({}_{5}\))\({}_{n}\), the theoretical ratio of oxygen atoms to carbon atoms in this material is 0.83. According to the study of the surface composition, it was lower than the theoretical value for all tested materials and ranged from 0.56 to 0.73, with the lowest value of the O/C ratio observed for the sample obtained after 480 s of plasma exposure. The highest O/C ratio was observed not for a pure cellulose sample, but for a sample exposed to plasma for only 120 s. Such relative enrichment of the surface with oxygen atoms can be attributed to the partial etching of the cellulose surface from \"adventitious carbon\" caused by argon ions. The high-resolution spectra of the XPS C 1s lines acquired for all examined samples are presented Figure 2. A deconvolution model which consists of four basic components of C 1s transition was applied. The component denoted as Comp (**1**), having a binding energy of 285.0 \(\pm\) 0.1 eV, essentially corresponds to nonfunctionalized carbon atoms. The component Comp (**2**), having a binding energy of 286.7 eV, is ascribed to a group of differently bonded \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{3}{c}{**IR Crystallinity**} & **HBI** & \\ \cline{2-4}
**Sample** & **A1372/A2900** & **A1429/A997** & **A3400/A1320** & **Index** \\  & **(TCI)** & **(LOI)** & & \\ \hline BC & 1.683 \(\pm\) 0.20 \({}^{\text{a}}\) & 0.993 \(\pm\) 0.17 \({}^{\text{a}}\) & 0.801 \(\pm\) 0.08 \({}^{\text{a}}\) & 0.683 \(\pm\) 0.02 \({}^{\text{a}}\) \\
120 s Ar\_BC & 1.685 \(\pm\) 0.04 \({}^{\text{a}}\) & 0.877 \(\pm\) 0.10 \({}^{\text{ab}}\) & 0.751 \(\pm\) 0.03 \({}^{\text{a}}\) & 0.667 \(\pm\) 0.01 \({}^{\text{ab}}\) \\
240 s Ar\_BC & 1.673 \(\pm\) 0.08 \({}^{\text{a}}\) & 0.849 \(\pm\) 0.04 \({}^{\text{ab}}\) & 0.899 \(\pm\) 0.10 \({}^{\text{a}}\) & 0.650 \(\pm\) 0.02 \({}^{\text{bc}}\) \\
480 s Ar\_BC & 1.492 \(\pm\) 0.10 \({}^{\text{b}}\) & 0.818 \(\pm\) 0.09 \({}^{\text{b}}\) & 1.266 \(\pm\) 0.15 \({}^{\text{b}}\) & 0.637 \(\pm\) 0.02 \({}^{\text{c}}\) \\
960 s Ar\_BC & 1.351 \(\pm\) 0.07 \({}^{\text{b}}\) & 0.766 \(\pm\) 0.04 \({}^{\text{b}}\) & 1.468 \(\pm\) 0.16 \({}^{\text{c}}\) & 0.611 \(\pm\) 0.006 \({}^{\text{d}}\) \\ \hline \hline \end{tabular}  
* The results are presented as means \(\pm\) S.D. The means with the same superscript are not significantly different, with \(p>0.05\).  
\end{table} 
Table 1: The values of the IR crystallinity indices (LOI, TCI), the hydrogen bond index (HBI), and the mass fraction of the crystalline allomorph I\({}_{\alpha}\) of pristine BC and BC modified by LPArP.