Assuming your data is in xvalu and yvalu
xvalu yvalu yvalu2 yvalu3 k_ast k_diff k_rc k_amp
0 0.0104 2.5896 0.0000 2.6000 -0.0273 -0.2057 2.6273
1 0.4459 2.1541 0.4885
2 0.8011 1.7989 0.8862
3 1.1477 1.4523 1.2100
4 1.3927 1.2073 1.4735
5 1.6954 0.9046 1.6881
6 1.9086 0.6914 1.8627
7 1.9831 0.6169 2.0049
8 2.0567 0.5433 2.1206
9 2.2272 0.3728 2.2148
10 2.2512 0.3488 2.2915
11 2.3140 0.2860 2.3540

Name all columns.
Guess what your asymptote is and enter into k_ast.
Enter into the yvalu2 column
=k_ast-yvalu
Enter into k_rc, k_amp, k_diff respectively
=LN(INDEX(LOGEST(yvalu2,xvalu),1))
=INDEX(LOGEST(yvalu2,xvalu),2)
=k_ast-k_amp
Do a Goal Seek to set k_diff to zero by changing k_ast
Your best fit curve is in yvalu3
=k_amp*(1-EXP(k_rc*xvalu))