The list of the modes can be obtained from RayTracingDebug.cpp or here is a snippet
"Radiance, "World Normal, "BaseColor, "DiffuseColor, "SpecularColor, "Opacity, "Metallic, "Specular, "Roughness, "Ior, "ShadingModelID, "BlendingMode, "PrimitiveLightingChannelMask, "CustomData, "GBufferAO, "IndirectIrradiance, "World Position, "HitKind, "Barycentrics, "PrimaryRays, "World Tangent, "Anisotropy, "Instances, "Performance, "Triangles, "FarField, "Traversal Node, "Traversal Cluster, "Traversal Triangle, "Traversal All, "Traversal Statistics, "Dynamic Instances, "Proxy Type, "Picker, "Instance Overlap, "Triangle Hit Count, "Hit Count Per Instance, "Light Grid Occupancy