Probing paper ageing by label-free fluorescence lifetime microscopy

Area of Science:

• Analytical Chemistry
• Materials Science
• Heritage Science

Background:

• Paper ageing is a complex, irreversible process affecting diverse materials.
• Current analytical techniques for paper deterioration have limitations in sensitivity, resolution, and applicability to historical artifacts.
• Non-invasive methods are crucial for analyzing sensitive materials like cultural heritage objects.

Purpose of the Study:

• To present a novel, fully optical, non-invasive method for monitoring paper oxidation.
• To demonstrate the utility of Fluorescence Lifetime Imaging Microscopy (FLIM) for assessing paper degradation.
• To establish a new diagnostic approach for sensitive materials.

Main Methods:

• Utilized label-free Fluorescence Lifetime Imaging Microscopy (FLIM).
• Measured intrinsic fluorescence lifetime changes in paper samples.
• Correlated FLIM data with Fourier-Transform Infrared Spectroscopy (FTIR) indicators of ageing.
• Validated the method on modern and historical paper samples under controlled oxidation.

Main Results:

• Intrinsic fluorescence lifetime of paper demonstrably changes with oxidation.
• Observed strong correlations between fluorescence lifetime shifts and FTIR indicators of paper ageing.
• Successfully validated the non-invasive FLIM approach on diverse paper samples.

Conclusions:

• The presented FLIM method offers a sensitive, non-invasive means to monitor paper oxidation.
• This technique provides a valuable tool for assessing the degradation of paper-based materials, especially in heritage science.
• Represents a significant advancement toward new diagnostic methodologies for material preservation.