An accurate measurement of the fundamental spin-spin relaxation time (T2) comes from the amplitude of the "spin echo" as a function of delay time (T). The experiment involves a 900 pulse that rotates the spins into the xy plane, where they precess at a range of frequencies due to the range of local fields. After the delay time T, a 1800 pulse is applied so that the spins that were ahead by precessing faster are inverted to become behind the spins that precessed slower. A large-amplitude spin echo occurs at an additional delay of T, when the faster precessing spins temporarily coincide with the slower precessing spins. D Question 1 2 pts When the delay time between the 900 and 180U pulses is T=5 ms, the spin echo (that occurs at a later time) becomes We of its initial amplitude. The resulting spin- spin relaxation time is T2 = ms. Question 2 2 pts The table (pasted below) gives the amplitudes of the spin echo as a function of the delay time between 900 and 180'J pulses. Fitting the data to an exponential delay(ms) Echo(V) 0.2 4.024 0.5 3.786 1 3.364 2 2.791 3 2.239 4 1.868 5 1.725 7.5 1.152 10 0.838 15 0.462 relaxation function yields a spin-spin relaxation time of T2 = ms