## 3 Results and Discussion
### Physical and Chemical Degradation
#### 3.2.2 FTIR Spectral Characterization and FTIR Indices
\begin{table}
\begin{tabular}{l c c} \hline \hline
**Index** & **Index** & **Value** \\ \hline Lignin Index & I\({}_{1590}\)/I\({}_{1508}\) & 4.040 \\ Carbohydrates/Lignin Index & I\({}_{1726}\)/I\({}_{1508}\) & 7.656 \\ Crystallinity Index of Cellulose Bands & I\({}_{1376}\)/I\({}_{2914}\) & 1.019 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: FTIR indices of the ancient wood samples calculated by selected FTIR absorption bands. Figure 5: **(a)**: FTIR spectra of the ancient wood. Red arrows indicate the characteristic bands for the lignin index (1590 cm\({}^{-1}\) and 1508 cm\({}^{-1}\)). Blue arrows indicate the characteristic bands for the carbohydrate/lignin index (1726 cm\({}^{-1}\) and 1508 cm\({}^{-1}\)), while green arrows point to the bands of cellulose crystallinity index (1376 cm\({}^{-1}\) and 2914 cm\({}^{-1}\), see also Table 2). **(b)**: XRD pattern of the wood sample. Soil particulates clearly appeared since they were mainly composed of calcite, gypsum and quartz in addition to the main beaks crystalline and amorphous cellulose at 20 = 15\({}^{\circ}\) and 20 = 13\({}^{\circ}\), respectively. hemicellulose tend to degrade more readily than lignin, leaving behind a higher proportion of lignin in the remaining wood structure [88; 96; 104]. The carbohydrate/l lignin index (given by the I\({}_{1726}\)/I\({}_{1508}\) ratio) revealed that the carbohydrate content represented by hemicellulose was very high in the sample, indicating a high content in hemicellulose with the lowest preserved lignin content [66; 102]. The lower carbohydrate/l lignin ratio of the sample (7.656) compared to the fresh wood standard (-8.5-10.0) [103] further confirmed the degradation pattern. This indicates a loss of carbohydrates (cellulose and hemicellulose) relative to lignin, which is a classic signature of wood degradation over time [85; 104]. The lower crystallinity index (1.019) compared to fresh wood standard (-1.5-1.8) [103] suggests a degradation of the crystalline cellulose structure. This is typical in archaeological wood as the more organized crystalline regions of cellulose break down over time [85; 103]. FTIR indices provided a detailed chemical analysis of wood degradation, revealing a complex process characterized by selective molecular breakdown. Overall, these results suggests a moderate to significant degradation, which is characterized by the selective loss of carbohydrates (cellulose and hemicellulose), relative enrichment of lignin content and breakdown of crystalline cellulose structures. The results show high hemicellulose content with relatively low conserved lignin, accompanied by lignin enrichment due to preferential degradation of cellulose and hemicellulose. The decrease in the carbohydrate-to-lignin ratio and reduction in crystallinity index indicate ongoing structural disorganization as the more ordered crystalline regions of cellulose degrade over time. This chemical fingerprint suggests a moderate to significant degradation pattern in which lignin remains relatively stable while carbohydrate structures gradually disintegrate. These results provide valuable insights into the state of wood preservation and long-term molecular changes. Such molecular disintegration leaded to reduced mechanical strength, increased brittleness and alterations in porosity and dimensional stability [85; 101; 102; 104].