Structural modifications of soda-lime silicate glasses using femtosecond pulse-laser irradiation

Femtosecond pulse laser radiation (250 fs, 1030 nm) of alkali and alkaline earth modified soda-lime silicate (SLS) glasses resulted in densification. The degree of density changes depends on pulse energy and glass-network connectivity. Raman spectroscopy study of the high-frequency region (800-1200 cm(-1)) confirmed that surface densification was the result of interatomic changes in the distribution of silicon-nonbridging oxygen (NBO) bond lengths and Si-O-Si bond angle distribution (BAD). Modifier valency contributes to structural rigidity and the degree of disorder a glass can incur during the deposition of high-energy laser pulses. Varying soda content caused larger shift in the laser modified Q(3)band position and width compared to the calcium modified system. Increasing laser fluence was found to affect the position of Q(3)Si-O stretching mode as well as the band width, indicating the increased degree of disorder laser pulses induce. These results underscore the role of modifier ions in the laser-induced densification of the SLS glasses.