[en] The low-energy structures of the radioactive nuclei ^20,21Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ∝5 x 10⁶ ions/s were accelerated to 1.7 MeV/A and Coulomb excited in a 0.5 mg/cm ^2natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for γ -ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For ²¹Na, Coulomb excitation from the 3/2⁺ ground state to the first excited 5/2⁺ state was observed, while for ²⁰Na, Coulomb excitation was observed from the 2⁺ ground state to the first excited 3⁺ and 4⁺ states. For both beams, B (λ L) values were determined using the 2⁺ → 0⁺ de-excitation in ⁴⁸Ti as a reference. The resulting B(E2) arrow up and down value for ²¹Na is 137±9 e²fm⁴, while the resulting B(λ L) arrow up and down values for ²⁰Na are 55±6 e²fm⁴ for the 3⁺ → 2⁺, 35.7±5.7 e² fm⁴ for the 4⁺ → 2⁺, and 0.154±0.030 μ_N² for the 4⁺→3⁺ transitions. This analysis significantly improves the measurement of the ²¹Na B(E2) value, and provides the first experimental determination of B(λ L) values for the proton dripline nucleus ²⁰Na. (orig.)