# Interferometric Deflection Analysis of Suspended 2D Polyaramid Thin Films

## TL;DR

A new optical technique measures how thin 2D films bend under pressure, temperature, and chemicals, replacing a more limited method.

## Contribution

A visible light interferometry technique replaces AFM for measuring 2D nanofilm deflection under extreme conditions.

## Key findings

- Multicolor interference patterns are translated into nanoscale deflection estimates using theoretical and semi-empirical models.
- The new technique allows studying 2D nanofilms under high pressure, high temperature, and chemically corrosive conditions.
- Optical microscopy becomes a widespread tool for analyzing nanofilm properties previously limited by AFM.

## Abstract

The 2D nanofilm bulge test, which uses an Atomic Force Microscope (AFM) to measure the deflection of a suspended film under various conditions, has emerged as an important measurement platform for understanding mechanical, barrier, and permeability properties of 2D materials as thickness approaches the angstrom scale. The problem considered in this work is the limitation of such bulge analyses imposed by the AFM whereby dynamic measurements under high pressure, high temperature, and chemically corrosive conditions are limited. In this work, a technique is developed for measuring nanofilm deflection using only visible light interferometry. Both theoretical and semi‐empirical models are applied to translate multicolor interference patterns from broadband excitation into estimates of nano‐film deflection, allowing nanoscale precision in most cases. The technique and algorithm advanced in this work allows the use of widespread optical microscopy to widen the study of these important 2D nanofilm systems to more relevant conditions.

A visible light interferometry technique is developed to measure the deflection of 2D nanofilms, replacing AFM‐based methods. Using theoretical and semi‐empirical models, multicolor interference patterns from broadband excitation are translated into nanoscale deflection estimates. This approach enables studying 2D nanofilms under high pressure, high temperature, and chemically corrosive conditions using standard optical microscopy.