We investigated the nuclear structure of ${}^{31}\mathrm{P}$ near the proton threshold using nuclear resonance fluorescence (NRF) to refine the properties of key resonances in the ${}^{30}\mathrm{Si}(p,\gamma ){}^{31}\mathrm{P}$ reaction, which is critical for nucleosynthesis in stellar environments. Excitation energies and spin-parities were determined for several states, including two unobserved resonances at $E_r=18.7\mathrm{keV}$ and $E_r=50.5\mathrm{keV}$. The angular correlation analysis enabled the first unambiguous determination of the orbital angular momentum transfer for these states. These results provide a significant update to the ${}^{30}\mathrm{Si}(p,\gamma ){}^{31}\mathrm{P}$ thermonuclear reaction rate, with direct implications for models of nucleosynthesis in globular clusters and other astrophysical sites. The revised rate is substantially lower than previous estimates at temperatures below 200 MK, affecting predictions for silicon isotopic abundances in stellar environments. Our work demonstrates the power of NRF in constraining nuclear properties, and provides a framework for future studies of low-energy resonances relevant to astrophysical reaction rates.

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• Hydrostatic stellar nucleosynthesis
• Nuclear astrophysics
• Nuclear reactions
• Nuclear structure & decays
• Nucleosynthesis in explosive environments
• Photonuclear reactions
• Polarization phenomena
• 20 ≤ A ≤ 38