Toward Probing Surface Magnetism with Highly Charged Ions

Round 1

Reviewer 1 Report

The aim of this manuscript is to probe the surface’s magnetic properties by measuring the x-ray emission produced in collisions of highly charged ions with the surface.  In the process of highly charged ions approaching the surface, since the captured electrons from the sample surface with the presence of a magnetic domain occupy half the orbital of the projectiles, the emitted x rays, when one of such electrons decays to a lower orbital, are expected to shift toward higher energy as compared to collisions with nonmagnetic surfaces. To fulfill this purpose, the authors have conducted a series of proof-of-principle investigations, which include the installation of the experimental setup, the calibration of the x-ray detector, and a preliminary result for the x-ray measurement with a nonmagnetic Silicon sample. The most important is almost all experimental techniques have been considered and finished, all of which are necessary to perform the x-ray measurements in the collisions of beams with surfaces. The work toward probing surface magnetism is very interesting, and the manuscript is well-written.

A minor question troubles me. In Figure 2, there are several values for the resolution of the detector at a fixed x-ray energy, and the values are different. It means that you measured several spectra for one x-ray transition, and the resolutions of these x-ray spectra were different. Why is the resolution's discrepancy up to 20 eV for example at the x-ray energy of about 7700 eV?

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper presents explorative data on the possibilities of using X ray emission by Ar¹⁷⁺ ions impinging on magnetic sample to probe surface magnetism. Not to complicate the first experimental steps here Si is used as a target to lay the ground work for the final experiments.

As the development of a new technique to probe surface magnetism with HCIs the manuscript deserves publication. The manuscript would benefit at some places from a bit of additional quantitative information.

minor comments/requests for further information:

page 1 line 28: Here, the purpose is to investigate the surface properties .... --> Here, the purpose is to investigate the possibilities to probe the surface properties

page 2 line 48 Here, our goal is --> Our goal is .....

figure 1 panel b. I find the addition of "Pauli exclusion" in the figure a bit confusing as it looks like it has something to do with the photon emission it self. More import in panel b all spins are aligned including the 1s, assuming spin conservation as the authors do any transition in panel b would be forbidden. I recommend to draw a spin down arrow in the 1s state for both panel a and b.

page 2 lines 56, 57 the shift of 177 eV is that based on calculations or earlier experiments, please add a bit more information or otherwise references.

page 2 line73 "qxkeV" I understand what the authors mean but it looks a bit weird

line 127 please check the use of singular/plural

lines 127-137: some extra information would be of benefit for the reader. In particular the choice of the fit function, e.g. does the spot seen by the detector plays a role or is it solely the overlap of the ion beam with the target, at which angle does the beam spot become larger than the target size. Why is there such a big difference between the mechanical alignment of the target to the ion beam axis. Why does the angle depend on the beam shape?

Figure 3 caption What is impinging on what at which energy. Add units to angle theta.

Finally some extra information on the conclusion in lines 149-151 might be in order. To what extend does this shift to higher energies due to a partial filling of the L shell relate to the anticipated shift from a magnetic sample.

Author Response

Please see the attachment

Author Response File: Author Response.pdf