Soft X-ray emission spectroscopy (XES) is a technique employed to investigate the electronic structure of materials by analyzing the energy spectrum of x-rays emitted from a sample. The technique involves exposing the sample to ionizing particles, such as electrons, and then measuring the energy distribution of the emitted x-rays. By detecting these characteristic x-rays, we can determine the presence of specific elements and be used for quantitative analysis. One type of optical dispersive element that can be used in XES is a reflection zone plate (RZP) [1], which is composed of concentric zones of varying thicknesses. RZPs act as diffraction gratings when x-rays are incident upon them, resulting in diffraction and interference of the x-rays, while simultaneously focusing them. Compared to other optical elements like periodic multilayers, RZPs offer higher spectral resolution and can cover wider energy ranges, and can achieve energy resolutions as low as 0.49 eV at the Al L2,3 line (around 72 eV) [2]. In this study, we employed a Fresnel RZP in an electron microprobe to detect Li K emission in different lithium compounds. Li K emission is a characteristic emission produced when Li 1s levels are ionized in the material. However, detecting this emission can be challenging due to its low fluorescence yield, re-absorption effects, and interference from other spectral lines in the same energy range. We reported the measurement of the Li K emission bands in several lithium compounds using an RZP spectrometer, demonstrating the potential of this approach for various applications in x-ray spectroscopy. Acknowledgment: This research was funded by Agence Nationale de la Recherche in the framework of the SQLX Project (ANR-20-CE29-0022). References [1]A. Erko et al., Opt. Express, vol. 22, no. 14, p. 16897, Jul. 2014, doi: 10.1364/OE.22.016897. [2]A. Hafner et al., Opt. Express, vol. 23, no. 23, p. 29476, Nov. 2015, doi: 10.1364/OE.23.029476.