Pandas - date string -> datetime -> float timestamp

import pandas as pd

df = pd.DataFrame({'date': ['04.01.2010', '05.01.2010']})

df['datetime'] = pd.to_datetime(df['date'], format='%d.%m.%Y')

df['nanoseconds'] = df['datetime'].values.astype(pd.np.float64)
df['seconds']     = df['datetime'].values.astype(pd.np.float64) / 1_000_000_000 # or 1000000000 or 10**9
df['seconds_int'] = df['datetime'].values.astype(pd.np.int64) // 1_000_000_000 # or 1000000000 or 10**9

print(df)
print('---')
print(df.dtypes)