The invention provides for stable and isolable cyclopropenylidenes of Formula I and stable and isolable cyclopropenylidene-metal complexes of Formula II, and methods of making thereof. The sense tube has a first end, a second end, and a sense hole formed adjacent the second end. The casing defines at least one indentation in the exterior surface, and the first layer is bonded to the third layer adjacent to the indentation. Measurements made by the detectors are partitioned into spatial bins defined by standoff and azimuth. A first prism sheet is secured inside the light-mixing chamber and is disposed parallel to the diffusion sheet.