The transition matrix elements between excited nuclear states provide valuable information about the structure of exotic nuclei. Lifetime measurements area model-independent way to deduce these matrix elements from experimental data.Two studies of proton-rich nuclei near mass 70 are presented herein usingadvanced lifetime measurement techniques.The first study is a measurement of the $8^+_1$ and $9^+_1$ states in the odd-$N$, odd-$Z$ nucleus $^{70}$As.The lifetimes of these states were determined by the application of the $\gamma$-ray lineshape method to $\gamma$-$\gamma$ coincidence data.The states were populated using with the $^9$Be($^{78}$Rb,$^{70}$As) reaction and$\gamma$ rays were detected with the Segmented Germanium Array in coincidencewith reaction products detected in the focal plane of the S800 Spectrograph.The $B(E1;8^+\rightarrow7^-)$ and $B(M1;9^+\rightarrow8^+)$ transition strengthswere deduced and were found to support the assignment of these states to a coupling of the odd proton and neutron in the $g_{9/2}$ orbital.The second study is a measurement of the $2_1^+$ state lifetime in the $N=Z$nucleus $^{74}$Rb. A novel technique called the Differential Recoil DistanceMethod was used to extract the lifetime from the $\gamma$-ray spectra. The next-generation $\gamma$-ray detector array GRETINA was used in theexperiment, again coupled to the S800 Spectrograph to detect residues from $^9$Be($^{74}$Kr,$^{74}$Rb) charge exchange reactions. The $B(E2;2^+_1\rightarrow0^+_1)$ strength was calculated and is consistent with the measured strength of the transition between the isobaric analogue states in $^{74}$Kr, which may be a signature of shape coexistence in $^{74}$Rb.
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