Measurement of anomalously strong emission from the 1s-9p transition in the spectrum of H-like phosphorus following charge exchange with molecular hydrogen

TL;DR

This study measures the x-ray emission spectra of highly ionized phosphorus and argon after charge exchange with molecular hydrogen, revealing unexpectedly strong emission in phosphorus that challenges existing theoretical models.

Contribution

The paper provides the first detailed measurement of the 1s-9p transition in H-like phosphorus following charge exchange, highlighting discrepancies with current theories.

Findings

Phosphorus shows twice the high-end Lyman series emission compared to argon.

Results deviate from existing theoretical predictions and previous experimental trends.

Measurement was performed with high-resolution x-ray calorimeter at low collision energy.

Abstract

We have measured K-shell x-ray spectra of highly ionized argon and phosphorus following charge exchange with molecular hydrogen at low collision energy in an electron beam ion trap using an x-ray calorimeter array with $\sim$6 eV resolution. We find that the emission at the high-end of the Lyman series is greater by a factor of 2 for phosphorus than for argon, even though the measurement was performed concurrently and the atomic numbers are similar. This does not agree with current theoretical models and deviates from the trend observed in previous measurements.