An isolated atom has four discrete energy levels: \(E_1 = -12\text{ eV}\), \(E_2 = -6\text{ eV}\), \(E_3 = -3\text{ eV}\), and \(E_4 = -1\text{ eV}\). Four possible single-step transitions between these levels are represented by labeled vertical arrows: Arrow 1 (from \(E_1\) to \(E_4\)), Arrow 2 (from \(E_4\) to \(E_1\)), Arrow 3 (from \(E_2\) to \(E_1\)), and Arrow 4 (from \(E_1\) to \(E_2\)). Which arrow represents a transition in which the atom emits a photon with the greatest momentum?