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The shear signal required for weak lensing analyses is small, so anydetector-level effects which distort astronomical images can contaminate theinferred shear. The Nancy Grace Roman Space Telescope (Roman) will fly a focalplane with 18 Teledyne H4RG-10 near infrared (IR) detector arrays; these havenever been used for weak lensing and they present unique instrument calibrationchallenges. A pair of previous investigations (Hirata & Choi 2020; Choi &Hirata 2020) demonstrated that spatiotemporal correlations of flat fields caneffectively separate the brighter-fatter effect (BFE) and interpixelcapacitance (IPC). Later work (Freudenburg et al. 2020) introduced aFourier-space treatment of these correlations which allowed the authors toexpand to higher orders in BFE, IPC, and classical nonlinearity (CNL). Thiswork expands the previous formalism to include quantum yield and chargediffusion. We test the updated formalism on simulations and show that we canrecover input characterization values. We then apply the formalism to visibleand IR flat field data from three Roman flight candidate detectors. We fit a 2DGaussian model to the charge diffusion at 0.5 $\mu$m wavelength, and findvariances of $C_{11} = 0.1066\pm 0.0011$ pix$^2$ in the horizontal direction,$C_{22} = 0.1136\pm 0.0012$ pix$^2$ in the vertical direction, and a covarianceof $C_{12} = 0.0001\pm 0.0007$ pix$^2$ (stat) for SCA 20829. Last, we convertthe asymmetry of the charge diffusion into an equivalent shear signal, and finda contamination of the shear correlation function to be $\xi_+ \sim 10^{-6}$for each detector. This exceeds Roman's allotted error budget for themeasurement by a factor of $\mathcal{O}(10)$ in power (amplitude squared) butcan likely be mitigated through standard methods for fitting the point spreadfunction (PSF) since charge diffusion can be treated as a contribution to thePSF.

Quantum yield and charge diffusion in the Nancy Grace Roman Space Telescope infrared detectors