Estimating Spatial Resolution and X-ray Radiation Dose in a Comparative Study of Composite Organic Nanoparticles Using Soft X-ray Scanning Transmission X-ray Microscopy and Soft X-ray Ptychography

Abstract

Scanning transmission X-ray microscopy (STXM) and soft X-ray ptychography (SXP) are powerful techniques for nanoscale imaging, offering high spatial resolution with chemical sensitivity. However, the interplay between spatial resolution and X-ray radiation damage remains a critical consideration for sensitive samples, such as organic materials. In this study, we quantitatively compared spatial resolution and radiation damage between the two techniques. Spatial resolution is assessed using Fourier ring correlation (FRC), applying both the 1/2-bit threshold and a signal-to-noise ratio (SNR) threshold mathematically computed for each spatial frequency. SXP achieves superior spatial resolution due to its phase-retrieval capabilities and enhanced coherent imaging properties. In this paper, a resolution of 20–25 nm with SXP at the nitrogen K-edge (∼400 eV) was achieved for the first time, while STXM is limited by zone plate used, outermost zone width as 25 nm giving a theoretical resolution of 30.5 nm (1.22 × outermost zone width). Moreover, in our measurements, we find that the X-ray radiation dose required for SXP is approximately 6 times lower than for STXM, leading to a remarkably low damage level, highlighting its potential for damage-sensitive studies. These findings establish SXP as a highly efficient and minimally invasive imaging technique for the nanoscale characterization of organic material.